Talk:Tesla Roadster (first generation)/Archive 1

Tesla not a good green choice?
You can have a vehicle with similar mileage, similar emissions and much better driving dynamics, range, reliability, confort and practicality for $60 thousand less!!!: http://www.worldcarfans.com/news.cfm/newsid/2070116.003/country/gcf/BMW/new-3-door-bmw-1-series-arrives ChuChingadas 20:08, 24 January 2007 (UTC)


 * And this helps improve the article how? Are you proposing a "comparison to other fuel saving vehicles" section? Because I don't see any mention of the tesla on that page. That car is not even a convertable, so the comparison to the tesla is like comparing apples to sandwiches. Plymouths 22:13, 24 January 2007 (UTC)
 * reinserting above comment. removing it was not cool. Plymouths 22:48, 4 February 2007 (UTC)

I don't understand...
 * 1) Much better driving dynamics? It goes 0-100km/h (0-60mph) in at least twice the time! The performance is not even remotely comparable...

 MaxDZ8 talk  10:23, 25 January 2007 (UTC)
 * 1) Much better emissions and mileage? Quoting: "economy improvements of up to 24 per cent compared to the previous model, while emissions have also been cut by up to 21 per cent"... how can this compare to a electric car which emits 0?


 * we will have to wait and see but very likely the battery heavy Tesla is not going to have better driving feel and handling as world-renowned BMW.


 * This point doesn't make much sense, since the curb weight of the BMW 1 Series is 1320–1450 kg, while the weight of the Tesla Roadster is 1140 kg


 * Electric cars don't have zero emissions. I won't explain why but will leave that as a homework assignment for you.


 * Yes, they have zero emissions. They emit zero pollution. If you are referring to energy production then say so rather than being smug. Ng.j 19:40, 8 March 2007 (UTC)


 * What you just said was: yes they have zero emissions but they also cause pollution. Duh.

Fire Risk
Just like the laptops powered by the infamous Sony Li-ion batteries, the Tesla Roadster is at a high risk of catching fire. That is why they need such complex electronics in order to redistribute electric loads and cool the batteries. It is a known fact that under hardcore driving the Tesla batteries may reach temperatures high enough that the chemicals inside the batteries will combust, making the banks of batteries either catch fire or explode. I fear for the lives of the drivers. A silicon valley company has as much experience making cars as Porsche knows how to make computers. They may end up being fined millions. Poemas 14:16, 15 May 2007


 * Tesla Motors has, as you point out, gone to great lengths to insure that the potentially hazardous li-ion cells in the ESS are well balanced, cooled and protected to minimize the risk of accidents. The ESS is not "just like the laptops" packs. Martin Eberhard's "Introducing Tesla Energy Group" blog entry explains that:


 * "We went through something like seven generations of design before we had what we consider to be a good, safe, reliable design. We validated this design with outside testing laboratories, and we demonstrated safety to the various cell manufacturers to convince them that they were not at undue risk of liability were they to sell us cells. We soon will demonstrate overall ESS safety in a series of United Nations-mandated tests so that we can ship production ESSes (and cars) over the ocean. We also recently performed the 50 mph rear-end crash test pursuant to FMVSS-305 compliance, which also is primarily concerned with battery safety."


 * More details can be found in the blog entries about batteries, the safety page and the white paper "The Tesla Roadster Battery System".  I have not seen any references to the "...known fact that under hardcore driving the Tesla batteries may reach temperatures high enough" for combustion.   The Tesla ESS would throttle back or even disconnect and shutdown if the cells became too wam.  Unfortunately, factual discussion about the inner details and design of Tesla Motors' ESS will likely be very difficult because the design details are closely held, trade secrets and/or in unpublished patent applications.


 * Gasoline is another hazardous material that ignites even more easily than lithium ion batteris. Many steps are taken to minimize the risk from gasoline as well, but it still causes the largest number of hazardous materials accidents in the USA.  All high energy density storage systems (gasoline, lithium ion packs, hydrogen tanks, explosives) are hazardous and need to be designed with safety as a primary consideration to minimize the risk from that hazard. Tesla Motors' seems to have done a great job lowering risk with the ESS. Mwarren us 07:50, 24 May 2007 (UTC)

..we can ship production ESSes (and cars) over the ocean... Please, please please, consider adding this to the article page! This means hope for us here in EU (I have just received an offer for a converted Fiat Doblo for a similar price)!

 MaxDZ8 talk  07:22, 26 May 2007 (UTC)

No Serious Car Magazine Reviews for Roadster Before December 2007
I was asking myself: "why aren't there ANY serious car magazines reviewing this car?" Then I found out there are, its just they aren't as favourable as the ones quoted in this article. Instead of respected car mags they have quotes from Businessweek and Forbes... give me a break. Where is Car & Driver? Where is Top Gear? Where is...

Its like asking a bind for directions. —Preceding unsigned comment added by Checkdance001 (talk • contribs) 18:39, 9 October 2007 (UTC)

Could you please link them here? I'm also interested in reading more.  MaxDZ8 talk  07:43, 10 October 2007 (UTC)


 * No "serious" car magazines have been given the opportunity to drive and test the car yet, therefore no serious car magazine reviews exist, as far as I know. Car & Driver has mentioned the car twice that I know of, but only as a future car, and not as a review. --Steve Pucci | talk 20:17, 12 October 2007 (UTC)


 * Motor Trend got to test drive the car on December 6th and Car & Driver checked the car out on December 4th. Except an article in Motor Trend's February issue. This is discussed on Darryl Siry's of Tesla Motors blog. BrandonG (talk) 09:39, 31 December 2007 (UTC)


 * In December, 2007 the list of magazines being given first drives of the Tesla Roadster Validation Prototypes included
 * Motor Trend (Kim Reynolds), Car and Driver (Csaba Ceres), Automobile Magazine, Road & Track (Jonathan Elfalan), and Auto Week (Mark Vaughn).  --Mwarren us (talk) 20:08, 12 February 2008 (UTC)

Remove list of colors?
I think the list of colors is way out of scope for an encyclopedia and is making this article somewhat cumbersome. Ideas? -- intgr 09:53, 24 July 2006 (UTC)
 * makes sense to me. removed. —Preceding unsigned comment added by 71.103.116.104 (talk • contribs)

Come to think of it, should the same be done to the 'Dimensions' section? I don't think it's really useful to anyone. -- intgr 23:39, 24 July 2006 (UTC)
 * Removed with a whole lot of other cruft. -- intgr 18:01, 27 July 2006 (UTC)

Speaking of removal, the "Criticism" and "Rebuttal" headers seem awfully like a pissing match, which should take place on the talk page, and not in the actual article. There should be a Criticism header, but the rebuttal points can be merged into it. Drogue 03:26, 17 December 2006 (UTC)

availability date?
I put it as 2007 in List of hybrid vehicles. If that is incorrect, please correct it and remove this entry. —Preceding unsigned comment added by 71.103.116.104 (talk • contribs)


 * It has already been removed as it is not a hybrid vehicle (eg, petrol-electric combo), but a battery electric vehicle. It's already on the list of production battery electric vehicles. -- intgr 18:00, 27 July 2006 (UTC)

AC Propulsion
It seems appropriate to acknowledge Wikipedia's promotional effects -- and use them to honor and promote innovation. We should allow readers to not just "follow the money" but "follow the innovation". That seems important in the same way the Connections (TV series) was important in offering an innovation-threaded view of history instead of the more tradional war & conquest-threaded views. (forgiving its similarities to People magazine)

The innovation contributed by AC Propulsion merits more than a footnote. It should nicely assist readers following innovation threads by citing AC Propulsion's contribution in the body of the article.

The link on the tZero page semed about right:

Some of the technologies developed for the tzero live on in the Venturi Fetish, the Wrightspeed X1, and in modified form in the Tesla Roadster

So I added similar text here.

--Lonestarnot 16:51, 2 August 2006 (UTC)

Please see my comments below explaining the revisions I made to this section. - David Vespremi

Fuel efficiency; gasoline equivalence
Although EV cars have much higher fuel efficiency than combustion engines, the calculations stated for the Tesla should be corrected in favor of primary energy equivalence. In essence, the formula as presented neglects the poor energy efficiency of electricity production of around 33%. The energy efficciency of the Tesla should therefore be multiplied by 0.33.

This would still yield fuel efficienies of almost 55m/gallon (against 164) or a consumptino of around 4.3 liters/100km.

These values are still good but not as fantastic (wrong) as the initial calculations. For the quality of Wikipedia primary energy efficiency should be used.

I havn't effected any changes in the main article yet because I would like to find a more reliable source for the electricity generation efficiency first. If someone finds it, go ahead.

--TomTompa 18:41, 24 September 2006 (UTC)

When I added the fuel efficiency section I too was concerned about choosing the "right" formula and the "right" values to use in that formula. For instance, the DOE regulation cites a generating efficiency of Tg=0.328, Tesla Motors' white paper cites another study's finding of 41% for the entire grid in one section and uses a third 60% generating efficiency in another section. Choosing the right formula is also of concern as it seems the end use of the derived number often drives the analysis. In any case, I could not figure out the formula behind Tesla Motor's 135 mpg figure (reverse engineering using 34.3MJ/L for gas & 110Wh/km for the roadster, convert, then multiply by 75% - a 25% "safety margin" - does yield 135 mpg. Interesting - how did they choose 25% safety?)

The first fuel efficiency equation was meant to be comparable to the typical Monroney labels' "station-to-wheel" efficiency (that label also omits well-to-station efficiencies). The second equation from the DOE regulation includes primary energy efficiency for both the USA electric grid and the crude oil to gas station path but then goes on to add a "'fuel content' factor" to quantify | conservation and scarcity of fuels in the USA.

The discussion of wide spread adoption of new fuel sources (e.g. electricity, hydrogen, bio-diesel, ethanol, coal gassification) certainly highlights the need for more extensive fuel efficiency analysis than offered by EPA City/Highway mpg numbers. One way for the Roadster article to handle this added complexity might be to simply reference Wikipedia's Fuel efficiency article or another (new?) article that can address the issue in more detail.

I digress, but hopefully the referenced article would describe several of the many aspects of "fuel efficiency" and provide names for those numbers. For instance, the article might discuss various views of efficiency as:
 * Monetary cost to the consumer per distance
 * CO2 emissions by the vehicle per distance
 * Fuel cycle CO2 emissions
 * Fuel cycle monetary costs (i.e. different subsidies and taxes might alter the monetary cost to the consumer)
 * Political costs of a given fuel to a nation-state

--Mwarren us 02:07, 25 September 2006 (UTC)

Moving this request for discussion from the main article:

"Using the average 8,000 Wh of energy per gallon, the 56 kWh battery capacity equals 7 gal of gasoline, so for the stated range of 250 miles this gives an equivalent of about 35 mpg; over an order of magnitude lower than the CAFE equivalent - clearly there needs to be some discussion about agreement on a standard of comparison since these values are so different. --User:67.174.240.33 20:44, 05 March 2007"

The figure of 8000 Wh/gal (presumed) is the amount of energy that a typical gasoline engine can extract from a gallon of gasoline input. The amount of energy initially available in the gasoline is closer to 33000 Wh/gal according to most sources (some cited in the main article). I've added a "citation needed" tag to User:71.202.108.49's 05:19, 25 September 2006 comment to ask about the source for the extraction efficiency numbers. Thanks for pointing out the problem in this section.

Using 33705 Wh/gal from the DOE results in an equivalent tank capacity of just 1.66 gallons of gasoline and 150.5 mpg (1.56 l/100km) using a bulk energy analysis (normalizing 250 mi/1.66 gal). Using Wh/km efficiency, the suggested bulk calculation yields 56 kWh/250 mi or 139.3 Wh/km on the EPA Highway cycle. This is certainly higher energy usage than quoted in the white paper. I don't think that Tesla Motors has explicitly cited the cycle they used to determine the Roadster's cited 110Wh/km efficiency, however, their footnote 8 (see below under "Wh/km") implies that the figure came from a 60mph constant speed test.

Update Mar 12, 2007: This discussion does point out a possible source for the 135mpg figure quoted by Tesla's press releases. The bulk 56kWh/250mi leads to about 130mpg for 33705Wh/gal gasoline.

Update Mar 14, 2007: See http://spreadsheets.google.com/pub?key=poDgN8KIZ_7q6mQqb2izMZQ for more detailed calculations.

--Mwarren us 23:03, 5 March 2007 (UTC)

Hopefully User:kslays will read this discussion page (update: yes! and read it quickly too. Thx!). To complete the cost analysis, some basis for the cost of gasoline per mile needs to be cited. Where did that come from? Thanks! --Mwarren us 02:23, 10 March 2007 (UTC)
 * I don't know how to make it look fancy with long fraction bars to keep track of the units, but here's a couple of ways of putting it:
 * (3.00dollars/gallon) / (0.01dollars/mile) = 300mile/gallon


 * (0.01dollars/mile)*(300miles/gallon) = 3.00dollars/gallon


 * If you think about it, if the Roadster uses 1 cent per mile, in 300 miles you will have spent 300 cents, or three dollars. The crux of my contribution (and the one I'm doubting) is the assumption of $3.00/gallon. At 3 cents, it's 300miles/$.03=100mpg.  Also, I need to cite the 1 cent/mile and 3 cents/mile, but I believe it's elsewhere in the article.  I'll do it tomorrow or Monday if nobody else gets to it first.  -kslays 02:41, 10 March 2007 (UTC)
 * Thank you for the update. I originally thought the article needed a citation for the gasoline engine cost/distance; but you covered the Roadster figures quite nicely and your equations here cleared up the confusion for me (Doh! to me).  Thank you. Mwarren us 05:23, 10 March 2007 (UTC)
 * ICE cost/distance is a separate issue that I didn't cover and so needs no citation. It can be calculated the same way though.  For a car that gets 30mpg, it costs 10 cents/mile to drive at 3 bucks a gallon.  $.10/mile*30mpg = $3.00/gal.  I've heard it costs about 15-30 cents per mile to drive most cars, including devaluation and wear and tear, but I have no citation. -kslays 15:53, 10 March 2007 (UTC)
 * Tesla Motor's FAQ says under the "Service" section that
 * "How much service does the Tesla Roadster require?"


 * "Far, far less than gasoline-powered cars. Most cars require service every 3,000 to 5,000 miles. The Tesla Roadster has no motor oil or oil filters to change, no smog equipment to check, no air filters to replace, no power steering fluids to refill. We feel confident that the only service your Tesla Roadster will require for the first 100,000 miles is tire and brake inspection. But we’ll be happier to see you once a year or every 25,000 miles or so, just to check in."
 * I think the statement "... the Roadster would cost the same to drive as a gasoline car..." would be more accurate by saying "...the Roadster's fuel cost would be the same as a gasoline car...". Maintenance costs seem to me to be a separate issue from Fuel Efficiency and might warrant a separate paragraph.
 * --Mwarren us 17:04, 12 March 2007 (UTC)

Full-cycle Energy-equivalency
First, thanks Mwarren us for all the work you're doing to improve this article. The well-to-wheel full-cycle energy-equivalency analysis doesn't seem right to me because the mpg equivalence numbers are so low. The wiki article on full-cycle leads me to believe it is an attempt at comparing the 'total' cost of energy to run the vehicle. For an electric car, that should include mining the natural gas/coal/etc., trucking it to the power plant, turning it into electricity, transmission losses to the plug, and efficiency of the car. For a gasoline car, this should include the mining of the oil, trucking, refinement energy cost, trucking to gas pump, and efficiency of the car. The numbers people are posting on the Tesla blog say it costs 12kWh to refine a gallon of gas, which alone would power the Roadster for 50-60 miles. And that's not even counting burning the gasoline for electricity! Now to dig around for a ref for that refinement value... -kslays 15:49, 15 March 2007 (UTC)
 * Thank you - I've tried to negotiate a middle way through many different opinions. It would be nice for the Roadster's full-cycle energy efficiency be higher, however, the Roadster does compete with Ferraris and Porsches; I wonder what the full cycle energy equivalency is for the competition! All of the factors you mention are discussed in the DOE report in | Federal Register Vol. 64 No. 113 (already cited in the article) and I included more opinions about them in my response (above) to User:TomTompa. It's a really big topic, but not exactly specific to the Roadster; it's just that the Roadster gets the discussion going. Here is probably the most relevant section from that DOE report:
 * "'.... Therefore, the PEF (petroleum equivalency factor) includes a term for expressing the relative energy efficiency of the full energy cycles of gasoline and electricity. This term, the gasoline equivalent energy content of electricity factor, abbreviated as Eg, is defined as:"


 * "Eg = gasoline-equivalent energy content of electricity = (Tg * Tt * C) Tp where:"
 * "Tg = U.S. average fossil-fuel electricity generation efficiency = 0.328"
 * "Tt = U.S. average electricity transmission efficiency = 0.924"
 * "Tp = Petroleum refining and distribution efficiency = 0.830"
 * "C = Watt-hours of energy per gallon of gasoline conversion factor = 33,705 Wh/gal"
 * "Eg = (0.328 * 0.924 * 33705)/0.830 = 12,307 Wh/gal"


 * "The derivation of these values is straightforward but lengthy and is therefore not discussed in this notice. Details on the assumptions, calculations, and data sources used to derive these values are described in materials contained in Docket No. EE–RM–99–PEF...'"


 * I wish the docket materials were also available online. These numbers are for the average USA electricity grid. That grid will become more efficient as it adopts the latest, 60% efficient Advanced Turbine Technology and power plants can more economically scrub their emissions.  Even better, individuals can choose to use even cleaner electricity. For example, if a particular Roadster is charged using "green" power (solar, wind, hydro, tide, geothermal, etc...), then its' specific petroleum equivalent efficiency is nearly infinite as no gasoline is involved when refueling the Roadster.Mwarren us 20:00, 15 March 2007 (UTC)
 * How would you calculate the full cycle energy use for an ICE car that gets eg 30mpg? What is the ICE formula?  How do you add in the energy cost of drilling, transporting, and refining the gasoline?  I think the numbers are misleading if left alone without comparison on the Tesla Roadster page.  Perhaps we could say, "For comparison, the Porsche 911's full cycle energy use is XXmpg and the Toyota Prius' is XXmpg." -kslays 20:08, 19 March 2007 (UTC)
 * I've done a few web searches (varying these terms: well-to-wheel mpg (toyota OR ford OR honda) ~refine ~transport (~drill OR ~well OR ~mine)) and haven't been able to come up with any way to calculate well-to-wheel numbers for ICE vehicles. It's really not an apples-to-apples comparison to state the Tesla Roadster well-to-wheel mpg which people will compare with the tank-to-wheel mpg numbers commonly used for their ICE.  The article needs to either give some well-to-wheel mpg comparison numbers for common ICEs, or list only the tank(battery)-to-wheel mpg efficiency equivalent for the Roadster.  Any thoughts on this? -kslays 18:09, 20 March 2007 (UTC)
 * Here are some links:
 * http://www.transportation.anl.gov/software/GREET/index.html
 * http://www.transportation.anl.gov/software/GREET/sample_results.html
 * http://www.transportation.anl.gov/software/GREET/greet_1-7_beta.html
 * http://www.eere.energy.gov/vehiclesandfuels/epact/pdfs/ghg_guidance.pdf
 * http://www.transportation.anl.gov/pdfs/TA/273.pdf
 * -kslays 21:23, 21 March 2007 (UTC)


 * The factor "Tp = Petroleum refining and distribution efficiency = 0.830" from the DOE regulation accounts for the "well-to-station" portion of the gasoline fuel cycle in the USA.


 * To convert a standard Monroney sticker value to a full cycle energy equivalent, convert with Tp.  For example, the Toyota Prius achieves 55mpg and uses 381Wh/km (assuming 33705 Wh/gal gasoline) station-to-wheel. To get the full cycle value, multiply mpg by Tp=0.83 to account for the refining and transportation energy use - 45.7 mpg, or divide Wh/km by Tp=0.83 - 459 Wh/km full cycle. The same adjustment applies to all vehicles fueled completely with gasoline (including of course the Prius), therefore, Monroney sticker numbers can be compared to each other with or without the adjustment.  The 329mpg, 49mpg and 87mpg numbers for the Roadster already include the 0.83 factor and can be directly compared to EPA sticker numbers.


 * When other fuels with different full cycle efficiencies are introduced, more complicated comparisons are needed. Another way to compare vehicles' full cycle energy use might be using Wh/km. Charging the Roadster with electricity from the "average" USA electric grid (efficiency = Tg * Tt = 0.328 * 0.924 = 30.3% ) means that the full-cycle energy use is 133 Wh/km (tank-to-wheel) / 86% charger efficiency (station-to-tank) / 30.3% (well-to-station) = 512 Wh/km full-cycle.


 * Interestingly, gasoline has a more efficient (83%) "well-to-station" energy cycle than the USA electric grid. Tesla Motor's white paper "| The 21st Century Electric Car" includes more examples, mentions that diesel fuel's "well-to-station" efficiency (90.1%) is even better and uses 52.5% efficiency for a natural gas powered electric grid. Oh, and depending on the specific study cited, these efficiency numbers vary. Mwarren us 00:00, 22 March 2007 (UTC)
 * Thank you. That's a very helpful explanation. -kslays 02:50, 22 March 2007 (UTC)

CO2 Emissions
What would be really useful from the perspective of comparing the environmental impact of the Tesla Roadster with other cars - but I'm not sure I've calculated it correctly - would be a comparison of the full-cycle CO2 emissions of the Tesla per mile/kilometre compared with petrol or hybrid cars. I've found figures indicating that the average CO2 emissions of the US electric grid are 1.34lb CO2/kWh = 0.61kg CO2 per kWh delivered. EV World Blogs If that's correct (is it?), the total CO2 emissions of the Tesla on the EPA combined cycle would be 81g CO2/km. That can be compared with EU combined cycle figures of 104g CO2/km for the Toyota Prius, 109g CO2/km for the most efficient small petrol car and 196g CO2/km for the Lotus Elise, which is the car the Tesla Roadster is based on. Car CO2 emissions I don't know if EU figures are well-to-wheel, or tank-to-wheel. I also don't know how comparable the EPA and EU combined cycles are. Simon d 12:35, 26 March 2007 (UTC)

The EU figures quoted above are tank-to-wheel. Well-to-wheel is about 12% higher.

I've now got some consistent EPA figures to do the calculations with. The Prius has an EPA combined MPG of 55 and the Elise has an EPA combined MPG of 26 (according to www.fueleconomy.gov). The EPA says that driving the Prius 15000 miles a year would emit 3.4 US tons (3.06 tonnes) and the Elise would emit 7.1 US tons (6.4 tonnes). The Tesla should emit 81g/km x 1.602km/mile x 15000 miles = 1.95 tonnes (2.16 US tons). That implies that the emissions of the Tesla are 63% of the Prius and 30% of the Elise. 55/0.63=87.3 and 26/.30 = 86.7. That implies that the CO2 emissions of the Tesla are equivalent to those of a petrol car achieving 87mpg on the EPA combined cycle. Shouldn't that go in the article? Simon d 15:45, 26 March 2007 (UTC)


 * Tesla Motors' paper "The 21st Century Electric Car" (pdf), page 4, also has CO2 calculations for six high efficiency cars along with their assumptions and references (their figures lead to 41.6 g/km for the Roadster). Well-to-Wheel Analysis of Greenhouse Gas Emissions of Automotive Fuels in the Japanese Context - Well-to-Tank Report from a Toyota research group has a very nice chart comparing CO2 emissions. For novel, concise and eye-opening information, Martin Eberhard's presentation from his Technology Comparison blog entry has even more ways to compare the environmental impact of driving.


 * Asking "If that's correct (is it?)", however, really goes to the heart of the matter; full-cycle analysis seems to mostly be lengthy and full of assumptions which can greatly alter the outcome of the analysis. I'm not sure this article is the right place to discuss all of the different ways to analyze the efficiency of automobiles. The Tesla Roadster does upset some common assumptions and thus instigates a lot of conversation. How about creating a new article to cover these topics?  Some suggestions for the new article and topics for it to cover are  listed above. Also, it probably makes sense to put in more prominent references to the Tesla white paper and to Mr. Eberhard's presentation for more information. Mwarren us 02:08, 27 March 2007 (UTC)


 * Added more prominent references to Tesla's "The 21st Century Electric Car" and to Mr. Eberhard's presentation.Mwarren us 23:40, 27 March 2007 (UTC)


 * Thanks for your comments and the references you gave. My quibble with Tesla Motors' own calculations for the CO2 emissions is that they assume electricity from a 60% efficient gas power station. It has much lower emissions than the average emissions of electricity generation in the US or even in California. I read (but I can't remember the reference) that electricity emissions in California are around 400gCO2/kWh. That would make the Roadster's emissions 53gCO2/km (equivalent to 133MPG), compared to the 41.6gCO2/k Tesla Motors quotes (equivalent to 170MPG). Average US emissions would be the 81CO2/km (equivalent to 87MPG) I quoted above. It's really just a question of where the electricity comes from.Simon d 23:18, 2 April 2007 (UTC)
 * The efficiency of the upstream power generation makes a much bigger difference in CO2 emissions than it does for the gasoline fuel cycle. That's one of the reasons to include Fuel Efficiency calculations for both the average US grid as well as for the 57%-60% efficient turbines coming online. I think that Tesla Motors is trying to make the point that as cars transition from gasoline fuel to electrical fuel (gradually with time), they will create a new demand on the electrical infrastructure and planning should anticipate what kind of new power plants will be built to meet the new demand from cars.  The DOE news release referenced in the article - "Advanced Natural Gas Turbine Hailed as Top Power Project of 2003" - says that "Natural gas turbines are expected to make up more than 80 percent of the power generating capacity to be added in the United States over the next 10 years."  (As an aside, in theory, GE's new Series H CCGT turbines can achieve 60% efficiency, but the reports of actual operation that I've read so far max out at 58% efficiency).Mwarren us 05:56, 4 April 2007 (UTC)

Update section with November 2007 Restated EPA Numbers?
The new testing numbers using the EPA test cycle - 31 kWh/100 mi - announced by Andrew Simpson (Tesla Motors Vehicle Systems Engineer) and the Tesla FAQ both indicate that the station-to-wheel, EPA Monroney sticker value will be closer to 98 mpgus (click for calculations) instead of the originally announced 135 mpgus. Before updating the Fuel efficiency section, however, I'd like to get more input here. Thanks! --Mwarren us (talk) 03:16, 14 February 2008 (UTC)
 * It's fine to note what Tesla claims, but we must make it clear that's their opinion, and not report it as an EPA figure until it's actually at EPA.gov. Superm401 - Talk 07:02, 15 February 2008 (UTC)
 * OK. I've updated the calculations to use the latest 221 mile range done on an EPA combined cycle test. The charging efficiency of 71.4% is based on email from Tesla Motors confirming th the Wh/mi used plug-to-wheel. --Mwarren us (talk) 17:39, 28 February 2008 (UTC)
 * Googling "site:epa.gov tesla roadster" or "site:epa.gov plug-to-wheel" gives no results. Why is that if the mpg rating for the tesla roadster is from the EPA?  I'm interested in official Wh/km to mpg or L/100 km equivalence.  I haven't come across such conversions from the EPA yet.  Ephdot (talk) 20:59, 31 March 2008 (UTC)
 * I tried to word things to avoid the impression that the efficiency numbers are official. The tests were reported to have been done in an EPA certified laboratory using the certified procedures and equipment, however, it seems the numbers have not yet been officially reported. Is there a specific section in the article that we should update to clarify this? --Mwarren us (talk) 16:21, 3 April 2008 (UTC)
 * This quote from the article: "135 mpg equivalent, per the conversion rate used by the EPA" is from a report which cites no sources and frankly, I can't find any "mpg equivalent" conversion rates from the epa. Tried to google "site:epa.gov  mpg-equivalent" - no results.  Does such a conversion exist and if so, where?  If not, this quote should be removed from wikipedia.  Ephdot (talk) 14:18, 4 April 2008 (UTC)