My baby hates being in carseat?

Once moving totally fine.the second we stop freaks.hes 3months old so hes in it for food shopping/running errands and cries the second I stop the carriage.I figure in stores I will just carry him til he can sit on his own and long drives(drove 6 hours once no prob til we got off high way.) I mean literally the second I stop driving he starts the second u start driving he stops.I feel awful for the poor kid.doeant mind the swing or bouncy seat if I ever put him in those.on the flipside he sleeps 10 hours at night so I guess this us my trade off? I'll take it! Just feel so bad for him.any ideas or advice?