A customer who tried to import his Tesla Model S to Singapore was surprised when the idiosyncratic city-state slapped him with a tax of around $11,000, rather than a tax rebate of around the same amount. The reason was even more surprising: because it polluted too much.

Singapore taxes cars based on how much they pollute, including pollution created generating the electricity used by electric cars. The taxes are designed to promote EV use, and explains why the Tesla owner thought he would get a rebate, as the Model S is considered part of the cleanest class of cars available in Singapore. However, when Singapore's Land Transport Authority tested the Model S, it found that the car was consuming 444 Wh/km, far above the 181 Wh/km that Tesla claims it consumes.

Tesla was surprised too. In a statement, a company spokesperson said "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."

Tesla says that at 181Wh/km, the Model S "emits" 90g of CO2 per kilometer, while a similar car — the Mercedes S-Class — emits around 200g CO2/km.

Tesla founder Elon Musk has been talking about these sorts of issues for years, noting that even if electricity is generated by a hydrocarbon source like natural gas, the inherent efficiencies of producing energy at a huge power plant far outweigh the CO2 generated when compared to an internal combustion automobile. Using renewable sources like hydro, wind, and solar makes the comparison even more favorable for the electric car.

The electric car company says it is in discussions with Singapore's Land Transport Authority 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."