rabbitgoo Tactical Dog Harness for Large, Heavy Duty Pet Harness with Handle, No-Pull Service Vest Large Breed, Adjustable Military Dog Vest for Training Hunting Walking, Grey, L

You might not have the same issues I have, because I have a convertible, but just search on amazon for seat belt harnesses for dogs. I buckle mine in any time the weather is nice enough to put the top down. He's learned where he's allowed and no longer tries to climb up to the front seat. I initially tried a seat cover w/ a barrier, but that barrier doesn't really work in a convertible (no roof for it to attach to) and he broke the barrier part anyway. I still use it because the seat cover is important, but the barrier part was always useless for me. For keeping him in place, I'd recommend something where you can buckle him in... might be a multi-part solution... dog seat belt + Harness (don't buckle in a collar) + seat cover w/ a pass through for the seat belt (that's the one I have, and like I said it works great as a seat cover, not so great as a barrier to a dog that wants through, but YMMV because I'm in a convertible so it was never really set up correctly to begin with).