When we first got Topher at 16 wks old, he just
hated going in the car and would get the exact same way...panting and just not happy to be there.
I still took him everywhere with me...errands, etc., and now he's almost a year old and he LOVES going in the van. He sits in his car seat and looks out the window and when he gets tired he'll have a nap (though this doesn't happen too often as it seems he hates to miss anything
)
I think if you just give it time and take him on lots of short trips, he will probably get used to it.