Ok so here is another update of the bmw just trying to get everything just right. I rendered it at 1000 samples about 5 hours of render time the only tweeking i did in the compositer was for the headllights glow so critique plz and if there are any suggestions fire away.
Looks a lot better, but still has some of the same issues. At least now you can see that all of the layers in the previous render weren’t doing you any good 
First thing I noticed is the car is stood on ‘tiptoe’. 
Car tyres flatten slightly, due to the weight of the car, when they are on the ground
There are a lot of geometry issues; the lights look boring, just two bright areas where each headlight should be.
It’s a good attempt at modelling but you needed to fix the geometry before spending so much time on your rendering.
Now I know you don’t have anything inside the car, but the windows could have been made more believable - see what I’ve done with my current project; it’s the first I’ve not done any interior for. Some very dark glass would work well.
I don’t see any windscreen wipers, although maybe they’re not visible from that angle?