While fighting the big tank at the end, go up any of the ramps to the higher levels. Hide behind one of the four shield generators, then an intermission sequence wil show the tank firing homing rockets at you. Do not move yet. The tank will now fire lasers at you, which can sometimes come through the walls. Reverse so that you are not hit and destroy the shield generator. Move to the next one after the lasers have finished and repeat the process. If you get badly damaged, go to the garage and change vehicles. However, this can be done with the one vehicle. When all the shields are down, the tank can now be destroyed. Do not get too close or it will fire grenades at you. Use the plasma. Run as soon as the tank says "Preparing homing rockets", then attack it again.