There is an issue for me with the badge awarding on this game for both easy and hard. Nice game though! The "expert" level is probably a bit too particular with the timings of things, but at least there are some checkpoints.
Challenges are rather hard. You probably need about 20 of the 24 achievements to have enough cash to upgrade the car. I think the challenges are in order of difficulty. The last one requires the most upgrades. To survive I think a good strategy is to let the police cars go ahead and hit the barriers. Watch out for the police cars coming from behind when the ones ahead die. Focus on dodging the mines. I managed about 1mile/min, and got to around 10 miles before dying. I don't think I'll do that again in a hurry!
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