Balance is very important. Try to keep you car perfectly balanced. Also consider how your car will be balanced after it loses parts. Take care of the power core, thrusters and weapons. Consider placing the power core at the center to prevent it from being destroyed easily. Surround thrusters with many blocks to keep them safe. Place the weapons at the back to keep them safe from incoming debris and enemy fire. Consider wrapping the core inside the thrusters and build the rest of the car around that. Try to make compact, box-like design. The more compact the vehicle, the better it will hold. Use as many blocks as possible. The more you have, the more survivable it will be.