buggys have acceleration more then anything, just a little extra top speed i think but its more fun to stop and take out the enemy camps + you can pick up supplies, ammo and health. gives you something to do while traveling
No it's not fun, it got boring after the 3rd time or so... I don't want to do anything except to travel to the target, I'd love to blast through a CP @ top speed and get away, but as someone said, the ai will always catch up anyway and you have to stop to kill the ****ers

Also no matter how many you kill, they will always be back, you could kill 1 billion people ingame, there'd still be enough oddly to restock the CP's with fresh soldiers who will shoot at the sight of you...