Ukraine has a reasonably developed system of major roads and the number of foreign nationals deciding to travel to Ukraine by car is on the increase. However, Ukrainian roads are not as well marked as in Western Europe and road signs are mostly in Cyrillic. Major Ukrainian cities suffer from frequent traffic congestion and confusing street layout. Seat belt rule is now enforced everywhere in Ukraine. Although the recent disbandment of infamously corrupt traffic police called DAI has reduced the threat of being stopped for "documents checking", the risk of getting stopped by police for no apparent reason is still high, and especially if your car has foreign license plates.
In Ukraine try to leave your car in watched car parks and do not leave valuables inside your parked car - a good habit to follow anywhere in the world.
When crossing Ukraine's western border be ready for delays. If you travel in an EU registered car, some border crossings now have lanes designated for EU cars on the Polish side of the border where lines could be shorter and processing faster.
Most Western car rental companies would not allow taking their cars across the border to Ukraine, so consider relying on your own car, taxis, Ukrainian car rental agencies, or hire a car with an English-speaking driver from Lvivecotour.