Stills can be looked at closely while animations run at 25 or more fps, so quality per. frame isn't as vital nor noticeable.
Lowering meshsmoothing density would be a major factor too if you are running low on memory - try the lowest quality just for fun. You could also, on top of mesh smoothing tweak, use VRMeshes. This feature is designed for memory hungry meshes when you don't have enough mem.
Not sure how shadow rays in VRay works, but reflection rays can also easily be limited to, as mentioned earlier 2 or 3 - think of it this way: Seing a reflection in a reflection in a reflection = 3 reflection rays. That's actually quiet a bit. Sometimes too much sometimes not. Depends on how big, flat and clean reflection surfaces you have. But again, 2-3 should be fine.
Re: not going to see it anyways - Look at poly amount this way: The closest rim and tire covers an area less than 150*160 pixels. Thats 24000 pixels. And since these meshes take up most of the polys I'm guessing a single wheel has something like 700k tris... or lets just say 500k - still, forcing 500k tris into 24000 is just never going to work. There's no gain in doing this. You can have 50k and see it looks better than 25k, but 500k is just too much.
Just try a few things - your render time was "only" 30 mins, so it should be OK to work with. Take long coffee breaks