As a safety issue, most movie cars are outfitted with fuel cells. In many cases, the factory tanks are completely removed and the fuel cells installed.
Most new cars have computer chips embedded in the key and, without this special coded key, the car will not start. Only auto dealers can make duplicates, and they can cost a few hundred dollars apiece. I'm not allowed to tell you how we do it, but we have a way of deactivating the "computer key system" so the car will start with "non-chip" keys. If a key is lost on the set, the production company can lose thousands of dollars waiting for a new key to be made by the manufacturer (imagine the high cost of production set time and personnel if they're waiting for a key to be made). We found a way to bypass the computer and use any key cut at our local key shop, and it was a huge breakthrough.
While not the simplest thing to deactivate, antilock means "antistunt" so that applies to any kind of stunt.
This is a connector that's mounted under the vehicle bumper allowing us to charge or start the car without having to use jumper cables directly to the battery. This is a handy feature that quickens car prep time.
We replace all stock seatbelts with Simpson lap and shoulder harnesses, and mount our own eyebolts into the floor with 6x6x1/2-inch steel plates as washers. This is overkill, but with used cars we want to make sure that a little bit of rust will not cause the seatbelt bolts to come out. In addition, the wider belts are more comfortable for the stunt drivers and hold us in place better.
A line lock is a drag-racing device that allows the driver to lock the front brakes while releasing the rear brakes. They are most often used for drag-racing burnouts to heat the rear slicks before a run. Line locks can be rigged to do everything from J-turns to locking up only the front wheels for some impressive movie-type burnouts.
Self-explanatory-hey, it's a stunt. Bigger shocks, sway bars, and springs are a must.
Simply removing the dome-light bulb will achieve the desired result. If you don't, because the temperature of the bulb light is different from the camera lighting, the actors will look red. In the past, we have also added a "gel" (colored film) to the existing bulb to change the coloration back to white light.
We all know what a rollcage is and why it's important, but on some movie cars we have to hide them so they will not be seen by the camera. The easiest way is to tint the windows. On the movie Twins, I had to build a high back seat that was a rollcage decorated to look like a seat so the Mustang convertible could be filmed driving on two wheels with the top down.
Windshields are barely enough protection from wind, let alone stunt materials. I remember one stunt where a tailpipe came through my windshield after tagging the stunt car in front of me. I usually put a Lexan or polycarb panel behind the windshield glass to add extra protection.
Airbags have to be disarmed for even the most minor stunts to avoid any possible injury during filming.
All warning and interior car alarms and buzzers have to be deactivated or the shot will be ruined.
Front 1-inch steel skid plates are bolted to the frame under the engine to protect it from damaging stunts. These skid plates are fairly easy to install, and we paint them black to make them less obvious to the camera.
Stunt people have a tendency to tap the brakes to test them before doing a stunt, and, if the brake lights come on before a stunt, the shot can be ruined. Most of the time, we solve the problem by putting the brake lights on a switch so they can be turned off just before the stunt.
There are a number of fire-extinguisher systems available, and we install them whenever there is any chance of fire.
Many older cars are equipped with rear drum brakes. With the repetitive stopping demands placed on movie cars, the brakes can heat up, causing a loss in stopping power. To give maximum braking potential, we swap out the drums for disc brakes and the problem is solved.