Sure, but that gasoline is also taxed. So, somebody who uses more gasoline because they have a less efficient car is also going to pay more taxes when they buy more gas.

And, even if there wasn't tax, subsidizing the production of gasoline as a whole is not the same thing as subsidizing an individual vehicle.

Gas isn't just used for personal vehicle use. Its used for infrastructure across the entire nation. Airlines alone use about half as much jet fuel and the general population does car fuel. We also use fuel for trains and trucking, construction, package/mail delivery, public transportation, etc.

The only vehicles that I know of getting subsidies are for electric or plug-in hybrid vehicles, which will decrease gas usage.