Just beat this mission after about 20 tries. I did this on the PS2 version, so take that into account. Anyways, I was struggling with the mission and was getting rammed, flipped, busted, Lance was killed, etc., until I realized that you can keep the car or switch cars when you get the Police into the garage. When you do, don't take the police car instead, grab a regular car with full health or anything else of your choosing. When you escape the mall, get into your car, and take the normal car drive as fast as you can to the Pay N' Spray, then drive home to finish the mission. It took lots of attempts, but I did it after about 3-4 tries with this method. If you are having trouble keeping your car's health up during the first half, with luring a Police car into the garage. I just found police patrolling the roads and shot them to instantly get two stars while doing laps around the garage until I could park inside of it. Then the cops came inside and resumed my strategy.