The ripple effect I am seeing is the opposite of what some of you are expecting.
There will be MORE newer cars sold. Because the fact that we are a car-based infrastructure is not going away any time soon. Drivers will wait to buy, which means they will be more capable of affording a more expensive automobile.
$100 beaters will go away, but will be crushed and recycled to make more new cars. This will create opportunities for high tech recyclers and brokers.
New cars will be more and more advanced, because drivers will be less and less capable, and more dependent on the nanny state. This will also push up car prices, which will push up comprehensive insurance rates.
These higher costs will push autonomous vehicles.
Taxes will continue to increase, as they always do. Fewer vehicles for young people will never mean politicians will become more capable of managing a budget.
Business for auto mechanics will INCREASE- owners will be less and less capable of basic maintenance. But the technical capabilities of the mechanics will also increase. This will mean increased wages for mechanics in the very short term, but not in the long term. Diagnostics and problem solving capability will transfer to the dealers and manufacturers. Mechanics will just be button pushers.
Roads and taxation will become easier and easier as the nanny state increases it's grasp on our day to day vehicle usage. We will be tracked, and charged for miles used, directly withheld from our paychecks.
Gasoline will begin being seen as a "dirty" fuel (much like diesel is today), and people won't want to pump their own. It will become more scarce, and major fuel manufacturers will transfer to being energy brokers, invested in other alternative fuel technologies.
Fuel prices will come down, not because of the taxes, but because of the need of the Saudis (and others) to sell the one commodity they have and can produce cheaply. This is OK by the government, because it is very easy to tax fuel imports at the ports. Arab states will push others out of the oil market (like we are seeing now), but other companies will get smart and quit trying to compete with them. They will become importers of foreign oil products, distributors, and energy brokers of various technologies.
Did I miss anything?