WOW! Fabulous !
This is one of the finest games in the sub-genre of upgrade-and-repeat games, i have ever seen.
The pros-
The upgrades actually make a significant difference each time.
They are modestly priced, unlike the outrageous prices in most such games.
The next stock car is faster and better than the previous one, fully modified, so you feel the difference right away.
Super wheel was the bomb! Loved it.
The cons-
The annoying zombie moans over and over again made my ears bleed.
It's not available on the app store for Android.
But otherwise, a fantastic game. Hope to see the sequel soon - with more cars and upgrades.
Cheers!