I can't say I was ever into Hot Wheels myself - maybe I'm too old and missed it as a kid, but when I saw Hot Wheels - Track Builder in the Amazon Appstore I had to check it out on my BlackBerry Z30. And I'm glad I did, as it's pretty darn sweet - and free.
As the name suggest, the game allows to you build your own custom tracks and this part is pretty clever, although I didn't really have the patience for it. There are however a selection of pre-made tracks which you can dive straight into and race and they are awesome! Once you select one of these, the camera angle will pan around the track so you can see how great it looks and how many times you are going to be upside down. You can skip the track preview if you desire and get right down to business.
Once it's time to race you'll utilize the BlackBerry's tilt controls to guide the car. Tilt forward to accelerate and left / right to steer. As you zoom around the track you need to collect coins to earn points and there are also blue bolts which give you a power boost.
Hot Wheels - Track Builder will offer you the option to sign in. Clearly, I didn't have an account so I set one up in the game which took less than a minute and once done I could then see that I had 2000 credits. These credits can be used to buy extra track parts and upgrade your car.
Graphics wise the game is pretty sweet and is backed up by some nice sounds and music. Overall, for a free game it's well worth checking out if you're into your cars.