Got few issues while driving in water.
1) There are few maps that you can't get out of the water easily, mostly experienced this in Tropic Island. It would be nice if the reset button R would bring you back on the road instead of spwning you at the place where the car is.
2) Steering is really hard in water.
3) There are few places at where you cant climb the shore to get out. Could that be designed to be slippery?
Respawn-at-last-checkpoint is planned for 0.6.4. As for points 2 and 3 these will become irrelevant when point 1 is fixed.
Please consider downloading and testing the 0.6.4 WIP (work-in-progress) version from the SourceForge SVN. You can get it easily from:
Code -> Download Snapshot
Then read the doc/BUILDING.txt file for building instructions and ask further questions if needed.