Put buttons on the wheels, so it looks like rims. Thats what I did for my car pack.

I like the police car but the truck beside it looks terrible

Nice start! Here's just a few ideas you might like to consider: 1.) Use a different block for the wheels, this helps to distinguish them, especially if the car is black- I use charcoal personally. 2.) In the real world, most motor vehicles have the same distance from the ground, also keep in mind that each block is 1 meter or 3 ft, so it is not necessary to raise the SUV off of the ground because it is not a tractor or monster truck. 3.) Consider using wool carpet to cover the charcoal blocks and the hood, roof, and trunk in general. Also add in details like hub caps, a front grate, headlights, doorhandles, and brake lights- as these are all common practice for building vehicles. I know I've said a lot of things that sound negetive, but they're just suggestions for a new builder. Have a diamond and happy building!

Good ideas!  Nice work!