You're right, there really doesn't seem to be enough of them it seems. Closest popular game that is 'vehicle combat' in recent years seems to be Mario Kart and the occasional Twisted Metal.
The Dev high-score was literally put in just before uploading about 2 hours before submissions closed (along with the high score system in general). If you can beat it, it changes some graphics on the main screen to celebrate outdoing me at (literally) my own game ;)