Fine. New policy.

We restrict the sale of new cars. We can make car zoning, so only SUVs can be purchased in some places, only trucks in another. Maybe in some small areas we'll allow sedans. Well Make sure that auto manufacturers can build the cars people want, or on the numbers they want them. Want a bicycle instead? Too bad, only cars are allowed here. People are walking? We'll just replace sidewalks with more road for cars.

Sure cars will become way more expensive, bit everyone who already owns a car can watch the value of their car go up!