Get in the car to the side and equip the Micro SMG or whatever sub or full machine gun you have, and start aiming at the drivers of the cars. This will be much easier than just shooting at the car and waiting for it to explode. You can ram into the cars to stun the driver to give you a clearer shot. Once you've taken out the first wave, a second should appear. After you've taken those out, the leader will appear with some gang members in the back shooting at you. Aim for the gunmen first and then the driver last, or you could just shoot the hell out of the car. If your car starts to have flames coming out of the hood, bail out. Blind rage can be helpful when you're out of a car, so bear that in mind. Also, remember there is ammo in the back of the drive-in, so collect it if you run out.
After all that hassle go talk to the manager. You can now buy this place for $100,000 If you have Montana Holdings it will cost you $90,000.