This does not prove the "car" is real. Since the permits are for existing Lexus SUV's, it only proves that there is some real "software testing". Said testing could be for Apple Maps data, it could be for the new iTaxi service, and it could be for a software platform Apple wants to sell to existing auto makers. It could also be for Apple buses designed to deliver employees to Apple's new campus, an automated Apple computer delivery service, or any number of other things.
But, it's probably for the Apple Car.
As for Apple "dropping the ball in traditional computer markets", I think that has more to do with complacency, pride, arrogance, or some combination of the three rather than other projects. Mac Pro engineers were not likely yanked off the job to go and design cars or car software, since the two have almost no similarities in design, use, or functionality.