Don't worry, I understand that completely, many years ago, during my married life, hubby was a classic car nut, spent way too many hours at car shows! Oh yeah, and been in the motor trade almost my entire working life too, for my sins.
So, first thing I would recommend is to fill the frame with the car - by all means get the record shots of the full car complete with people, but then, look for the interesting bits and get in close. So for example, lets take the yellow golf in the first pic. Headlights, when you look closely, are amazingly complex, so had you got more side on and in close [so that the grill disappears off to the back of the frame and oof] and focused on the actual facets of the lights - already more interesting and arty. if owner is around, ask nicely to turn a side light on and suddenly you have a chance of some interesting flare too...
Use reflections, so for example, if there is a really nice nice car reflected in a less interesting one and you can be patient for a few minutes until you can get a clean shot, focus on the reflection rather than eliminating it.
Look for tiny details, the sort of stuff most people would miss because they are too busy drooling over the entire car and focus in on those. Harder with these kind of cars I know because they are often debadged and generally trimmed down to look less cluttered, but some with have them. Also, swoopy styling lines going across an entire frame work really too, they become almost abstract.
Zoom lenses...how steady are you hands?
if you use a slower shutter speed, up the aperture to compensate the exposure, then twist the zoom as you click the shutter [use centre focus point to begin with, it takes some practice] you can get some really wacky fun effects - plenty of bin shots, but the odd one will look brilliant. Have a look at this blog post from a wedding I did, the last two photos used this technique on people, but nothing to stop you using it on a GTi badge, or a really cool alloy wheel
http://www.whitegoldimages.co.uk/fun-wedding-photography-at-fanhams-hall-in-hertfordshire/
Finally, YES, the crowds are a nuisance, but you are stuck with them, so use them, photograph the people too, obviously discreetly, look for expressions, humour, enjoyment, emotion and grab it
I hope that helps a little and gives you some ideas. I do know it is difficultand technically there is absolutely nothing wrong with your photographs, but having a play without any pressure to produce stunning photos is the best way to learn what can be done.