My Moose-dog is a nervous rider. When he was a puppy, he'd get carsick on a slightly windy or hilly road. I found in the SUV, he had the least problems if he laid down in the back. It allowed him to see outside, but by laying down, he reduced the wobbly feeling. Standing up was the worst thing for him (he's a tall thin boy and doesn't have a solid center of gravity when standing). I made sure to always take turns and hills slowly so that he wouldn't feel those sensations, and kept him laying down as much as possible. That helped a lot.
When I got the clipper, he got real nervous when I started it up. On the road, he felt so much more movement in the RV than in the SUV and it was much louder. I did short trips with him and watched to see where he had the least response to the movements and noise. When he laid down on the couch, he was the least agitated. He could see me, see out the windows, and felt the least amount of movement. Now, 3+ years later, he loves going in the clipper. He still has some stress if we go over the rumble bumps, etc. - when that happens, he will get up and come stand by my driver seat and lean against me for a few minutes while I pet him; then I tell him to go back and lay down and he hops back on the couch and relaxes. For him, I have found that not letting myself get upset with him helps the most. If I'm calm and relaxed, then he realizes he can be too.
His sister is short and squat and has an iron-clad stomach and never reacts to anything other than seeing people on her street (yes, if she's on it, it's HER street).