there is a major bug in solo campaign, when you kill 2 or more bikers in the same time, counter don't move ! exemple : 5 kill remaining, i have kill 3 bikers with uzi in the same time, and always 5 kill remaining.
the second bug is on steam success, it's impossible for me to unlock this 4 success :
-Raggety and Die -Road Ninja -Cash Money - Road Master
I took a short cut, I drove off of the bridge, on the little race status bar thing at the bottom I was way ahead of the finish line. Don't know if I really was or not because someone killed me, but according to that thing I was way ahead of finish line, with two skulls ahead of me.