In the US people start driving at 16, no? In Austria and Germany you can get an early license with 17.
I got my moped license with 15, but that is probably a hard sell in the north ...
I'd say reduce the age at which people can get a license, make drivers education better, and put a limit on horsepower (same way it is done with motorcycle licenses).
Also several of my friends got mopeds at 14 and would drive them around town. Not good for driving on gravel roads but was great for the kids in town.
The farm kids out of town would drive their parents trucks/cars in and around their property starting around 13/14 but that was generally to haul feed and equipment around.
There are limitations- an accompanying adult, number of non adult passenger restrictions to limit distractions etc, but the reality is they are still in control of the vehicle.
Out in the country, it is relatively common to drive yourself to school the last year or two. Trying to raise the age to 18 would not go over well at all!