There is really no reason to use the vehicle mode outside of designated area's where they are required. Anyone other than Scientist and maybe Infiltrator are just have glorified sprint that makes you more vulnerable than anything. A large part has to deal with the level design. The first few acts as Optimus has way to much clutter to make vehicle mode practical. With sprinting and dodging it makes the time it takes to get in and out of vehicle redundant. Your weapons mostly suck, your effective aiming range is lowered, and you are no more mobile than you were on foot. Try to transform and move around doesn't really work because enemies will always be right on your tail. Try to drive past or into enemies and they will shoot you up incredibly fast. Your weapons suck compared to the stuff on foot and the lack of specific vehicle abilities other than a button to slightly go faster really dulls the experience. The whole thing feels so much less fluid than the first game. Outside a nicer turning animation there hasn't been any real improvements. I was hoping they would improve the vehicles as much as they did the shooting, which still has issues thanks to the way enemies can suddenly damage you.