Agree with Macky's assessment.
To me, the one shot (of those you posted) that shows some promise is the first one of the Jeep. But somehow, it needed to be shot differently to really become a pleasing photograph. Next time take a few steps back... look through the viewfinder... and if you don't like what you see, don't be afraid to move again! Perhaps a higher vantage point would have worked well for this photo... looking over the hood/fender of the Jeep and down into the terrain it is about to go conquer. I'm just throwing ideas out at you... these are things you might try and like, or try and not like. Try it several different ways next time and review the results on the PC later. This gets your own creativitiy flowing... while reviewing your photos, you may think of new things you want to try next time. It snowballs from there.
Can't really do anything with the second pic since the focus is off. Interesting sky, but the camera underexposed, so the terrain features can't be made out. If that was intentional, a better angle or location should be used to get those distracting features out of the shot.
The third one... is a shot of nothing. Unless that is special dirt and weeds!
The shots of the 3000GTs are random at best... cars in parking lots, apartment complexes, dumpsters, halves of cars in front of stores... these are snapshots and not very good ones.
If you want to shoot cars, you have to be willing to move the car to an interesting location, or at the very least a location which provides no interference to your shot. Something like a parking lot, store, etc. is a distracting background at best, and at worst can obscure part of the subject or make the photo confusing.
Shooting cars at meets is particularly difficult for this reason. Very rarely are the coolest cars parked all by themselves with noone looking at them and a pleasing background.
Definitely agree with the others that for right now, the camera is not your limiting factor. Buying a more complex camera would only hinder your creativity at this point. I think the best you can do is push the button - A LOT - and review the results. And don't be afraid to move your feet and/or move the subject.