Fixin' the car problem

Instead of giving billions to car companies in vain, we should start providing subsidies for people buying a car. We will give out 80-90% subsidy for a vehicle meeting certain standards such as fuel efficiency, fuel type, and price.
We buy the vehicle and it stays with them but after they are done we take it back and return the 20% they paid in ensuring that vehicles will be returned in good working order. We can used returned vehicles for government use or give to poor families or young people.
By deciding the vehicles eligible by fuel efficiency and type we target a real goal. We want our cars to run on certain fuel we fully subsidize that type of fuel, people go for cars that fit that criteria and the car factories start churing the cars we want and we don't really bother with any oversight.
People that aquire cars like that will still pay registrations and all such fees encouraging whoever does not need a car to return it and get their 10-20$ down payment back.
And even subsidizing all the demand in the US it will cost us around 150 billion/year to do that. Funny amount if you think about it and in reality I think that even 50 billion will suffice especially in the first few years while the car companies can get up to speed with demand.