Since 1991, consumers have paid the Gas Guzzler Tax on every new car purchased or leased with an unadjusted combined EPA fuel economy rating less than 22.5 miles per gallon (mpg). This only applies to cars, not pickups, vans, or SUVs. The maximum tax for cars with fuel economy ratings less than 12.5 mpg is $7,700. Most of the models that are assessed the tax are sports cars or luxury models.
Note: Unadjusted fuel economy is based on only city and highway driving cycles, while the fuel economy on the window sticker is based on city, highway, three additional driving cycles, and an on-road adjustment factor.
Source: Internal Revenue Service, Form 6197, (Rev. 10-05), "Gas Guzzler Tax."