Honestly i would not choose the buggy. The hummer has a reasonable price, you can
take a whole group of players with you if needed, it gets deteriorated slowest of all cars,
speed is good at hills and deserts aswell, full consumption is low and trunk is really big.
You can drive from NCR to klamath and back to NCR, and still dont need a repair.
The scout is worst car of all, only can agree with that.
The buggy is fast as a vertibird, but only on desert squares. Especially at mountains
he looses speed, and it deteriorates really fast. Like you drive from NRC to klamath,
and probably need 1,5 repairs on the way.
Btw, you cannot use super-tool on cars, only the normal tool. But 120% is enough to repair any car.