Yeah, I gave it a quick go last night and found it way too slow. Didn't realise there were different cars and stuff though, so I may go back and have another look. Always loved Cubed Rally Racer.
What's the IAP mode like in this? It doesn't really say what it is
Yeah, it doesn't do a very good job at explaining it, but the coins you collect go towards cars which are rated between 1-3 stars. The stars equate to your starting speed, which is almost like a difficulty slider. The faster cars also string together more points while drifting. Try unlocking a faster car before giving up.
The only IAP I've seen is 99 cents to unlock a rally mode, which is 20 speed attack race courses.
There's probably some kind of IAP to buy coins to unlock cars, but I unlocked the fastest car without IAP relatively easily while completing missions.