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Tesla responds to Singapore’s Model S CO2 emissions test, and could it be as simple as poor math?


Last weekend we reported on Singapore’s Land Transport Authority (LTA) slapping an important tax surcharge on the Tesla Model S after running some emission tests and rating its energy consumption at 444 Wh/km. After accounting for Singapore’s grid emission factor of 0.5 g CO2/Wh , the LTA determined that the Model S somehow ended up on the worst end of the global city’s scale for vehicle pollution (C3 band).

Tesla has now issued a response (you can read the full statement below) and claims that when the Model S tested by LTA left Tesla’s factory in 2014 (yes it took a while to import it), it had an energy consumption rated at 181 Wh/km, less than half of what Singapore’s transport agency is claiming. How can we account for the discrepancy? 

LTA confirmed that if it would have used 181 Wh/km instead of 444 Wh/km in its CO2 emissions calculations, the Model S would have qualified for an incentive rather than a fine.

CO2 emissions for a Model S powered by Singapore’s electric grid:

  • Based on Tesla’s 181 Wh/km = 90 g CO2/km
  • Based on LTA’s 444 Wh/km = 222 g CO2/km

It is the difference between the Model S polluting less than half as much as a Mercedes S-Class in the case of Tesla’s calculations, and more than the gas-powered S-Class in the case of the LTA’s calculations.

Now how the LTA came up with that number is still not clear, though the agency says it using the United Nations Economic Commission for Europe (UNECE) R101 standards. Tesla says they are having “cooperative discussions” with the LTA to ensure they correctly testing the Model S.

With such a big difference, it’s difficult to image what happened to the Model S to be rated at 444 Wh/km. Cranked A/C? Heavy right foot? Some are even suggesting that it could be as simple as an error while converting from miles to kilometers:

[tweet align=’center’]

Could a simple mathematical error have caused this situation?

Here’s the full statement Tesla sent us:

The Model S that our customer imported into Singapore left our factory in 2014 with energy consumption rated at 181 Wh/km. As the Land Transport Authority has confirmed, this qualifies as the cleanest possible category of car in Singapore and entitles the owner to an incentive rather than a fine.

Model S achieves this result because CO2 emissions in gas-powered cars are far higher than in electric cars. In Singapore, electricity generation releases roughly 0.5kgCO2/kWh. Based on energy consumption in Model S of 181 Wh/km, this results in 90 g CO2/km. Driving an equivalent gas-powered car like the Mercedes S-Class S 500 results in emissions of approximately 200 gCO2/km. And because of oil extraction, distribution, and refining, approximately 25% more has to be added on top of that to calculate the real carbon footprint of gas-powered cars. That means an electric car like the Model S has almost three times lower CO2 per km than an equivalent gas-powered car. Moreover, as Singapore increases the percentage of grid power from solar and wind, the CO2 from electricity drops with each passing year. 

We are having cooperative discussions with the LTA to ensure a proper understanding of these issues and to make sure that they are correctly testing our customer’s Model S. Based on the positive nature of those discussions, we are confident that this situation will be resolved soon.

Until the issue is resolved, it is likely that Joe Nguyen’s Model S, the one used in LTA’s tests, will be the only Tesla on Singapore’s roads:

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  1. František Kubiš Jr. - 7 years ago

    It is not a big problem to get 444Wh/km. Just start the car, turn on AC and do nothing else. And after a while drive 1km and voila, record consumption per km achhieved 😀

  2. Kharan - 7 years ago

    I do seriously not get it… Why and how on earth are they calculating co2 emissions on an electric car with no tailpipe? If it is using electricity from renewable sources than it has true zero emissions, zero, nada 😀

    • Stetson - 7 years ago

      “After accounting for Singapore’s grid emission factor of 0.5 g CO2/Wh…”

      So they’re saying it isn’t running on renewable energy resources. Hardly seems fair to judge the car by their own electric grid though.

      Do they also account for CO2 emissions from refining and transporting gasoline? Or just the actual CO2 emissions of the cars?

      • Ryan - 7 years ago

        “approximately 25% more has to be added on top of that to calculate the real carbon footprint of gas-powered cars.”

        Straight from the article above lol.

      • Stetson - 7 years ago

        Yes, that’s from Tesla’s statement. I was wondering if LTA was factoring that in. Tesla seems to think not.

  3. James Rowland - 7 years ago

    I don’t suppose anyone at the LTA wondered why their numbers were so discrepant with what everyone else was getting…

  4. Nathanael - 7 years ago

    I would lay bets on bad math. The only other way I know to get those numbers is to take a frozen car which hasn’t been plugged in and measure the usage from startup without testing for very long (there’s a quick blast of heating at the beginning for the first mile), and I don’t think Singapore gets cold enough to do that.

  5. wky - 7 years ago

    these accusation have to be responsible by someone for the wrong math. otherwise they will keep fining everyone domestically even the world disagree to that accusation. like north Korea.

  6. Lt - 7 years ago

    They can’t find the MH370 either. The airplane flew over the country and they couldn’t pursue using a fighter jet.

    • Whut. - 7 years ago

      Lol the plane flew over Malaysia. If Singapore had sent a fighter after it, it could have started a war. You DO know that they’re two separate countries, right?

      • DjTeddySpin - 7 years ago

        it wont start a war. if there is a plane not designated to fly over respective territories, it is in every rights and safety of the sovereign country to enegage it.

        RSAF has 24hour standby units ever since after 9/11

  7. dcj001 - 7 years ago

    “With such a big difference, it’s difficult to image”


  8. Paolo Manno - 7 years ago

    I don’t know if the 444 Wh are more realistic than Tesla’s own figure. I do know that even a very small and lightweight EV like Daimler’s Smart-EV needs some 150 Wh. So Tesla’s claim is hard ti believe. Anyway, Singapore government correctly looks at the CO2 from power generation. This is too often neglected by EV promoters. 0,5 g CO2 per Wh is a figure that lies between a state-of-the-art natural gas plant and a coal-fired plant. The natural gas plant would have to be of the type that recovers energy from the waste heat after the gas turbine and drives a steam turbine from that. They are still rare but can get 60% efficiency and an equivalent of about 0,35 g CO2/Wh. From what I see on the Internet, Singapore has almost only gas plants but I don’t know if there are any of the most modern gas and steam type. So the 0,5 g figure may be quite realistic. The waste and solar portion of power generation there is very low, and it does not matter anyway as this generation always is exhausted even without EVs. Therefore any EV charging will have gas plants to be generate the charging power (the so called marginal power). This will not change even with a rising percentage of green power plants, as long as thode will be exhausted already at the time of charging the EVs. Maybe the Singapore government also knows that. Then this government must be really congratulated for its clear assessment. While most other governments worldwide are carried away by the myth of the emissions free EV.

  9. fpveritas - 7 years ago

    The LTA can play with the numbers all they want but Singapore is looking like a 3rd world country when it comes to EVs. This comes as a stark contrast to the high tech/innovation first world city state that they brand themselves to be. It’s not like there’s no one showing them the way – Hong Kong, their regional counterpart/nemesis, has one of the highest EV penetration rates in the world, like you stated.

    IMHO the people of SG are being shortchanged because of two situations:

    1) Singapore has a significant oil refinery and trading industry that amounts to 5% of its GDP ( and more importantly, it’s the leading energy hub for Asia ie. significant vested interest and high level relationships to maintain.

    2) The COE significance and momentum that every car owner despises will be threatened and this will wreak havoc with the car owner population. If they change the COE for EVs, this may cause considerable unrest. If they don’t change the COE, then there’s no government-led incentive to be innovative so EV’s may flop.

    So at the end of the day, do nothing and find ways to do nothing. Purely speculative on my part but having been a resident of this advanced city state, something doesn’t add up….more than just the LTA numbers.

    ps. the Tesla Model 3 opened up for pre-orders for Singapore…great to see and good luck.


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