I have a bit of a racing background so a few things are counterintuitive to me. You should slow down just from turning. Except in a very mild turn, you can scrub speed without lifting off the accelerator. Smoothness seems to count for nothing. Changing direction on a straight at full speed or twitching in a corner should upset the chassis or at least slow acceleration.
On the upside, playability is good. And I like the "tiger teeth" telling me which way the turns go. However, the big turn signs for the tighter turns really only need to be at the entrance of a corner, not all the way through.
Good concept. Needs lots of work. There's no meter to let you know how much power you have. That would add to playability. Also the map only partially forms, and winks out regularly.
I agree that it would be more playable with smaller, bite-sized chunks of game, but I was just getting over the lack of pause, the long level re-dos, etc, when I was chasing a bomber and left the mission area... thus failing the level. Again. Was 5 stars until then. Now 4/5.