A: Since your 2 month old is still in the newborn period of life, the nervous system hasn't had much time to develop. This means all kinds of sensations can make him uncomfortable, including the feeling of car seat straps, the smell of the car, and the motion of driving. Plus, you also can't hold him during a car ride -- all of this add up to a fussy experience.
With time, your baby will likely get used to car rides. Until then, try to minimize the time he must spend in the car; try to schedule rides for when he is likely to nap or when he's happy after a feeding. Of course, for safety's sake, always restrain him properly in the car seat. You can also let him hang out in the car seat at home so he gets used to the seat in a more familiar surrounding. If he's like my babies, eventually he'll love the car!