Ebbetts Pass and Highland Lakes: Car Camping Highway 4
Highland Lakes has a nice car campground, and across from it is a smaller set of sites between the Lakes to the Southwest.
Tahoe to Whitney Trail Guide
Stanislaus National Forest
There are a series of free car campsites on the East side of Ebbetts Pass just off the road that I've stayed at over the years. Though you don't need a permit to car camp in the National Forests, you do need a fire permit, even for camp stoves in many forests.
Post up information about your experiences car camping along Highway 4, Ebbetts Pass, and Highland Lakes.