A screwdriver is used to loosen and tighten screws. The DeLorean has mostly philips head (also known as cross head) screws, but it is useful to have a few sizes of philips and flathead screwdrivers handy. Screwdrivers come in various lengths and sizes depending on how accessible the screw is. Ratcheting screwdrivers act much like socket wrenches, allowing you to keep turning the handle without having to move it off the screw head first. There are many other kinds of less common heads as well, some of which are used on the DeLorean, such as the posidrive screws used on the clutch master cylinder, and the hex cap screws used on the engine.
Care must be taken to choose the correct size screwdriver for a particular screw. Although a driver (especially a philips driver) may appear to fit the screw, if it is too small it will only wind up stripping it and slipping, especially if the screw is in tight. Using the proper, larger screwdriver will allow you to get more torque and avoid slipping, while too large of a driver will slip off the head and not turn the screw at all. Be sure to use the correct size screwdriver when removing screws.
Screwdriver bit adaptors are also available for power drills, allowing different bits to be swapped in for a variety of tools. While these can be useful for many tasks, like removing the screws from the taillight assemblies or the shifter plate, care must be taken to avoid over-torquing the screws and destroying the threads in the hole. Similarly, it is easy to strip the heads of a screw with a power drill, making it hard to use any screwdriver to extract it again. Many modern power drills have an adjustable clutch to allow the drill to slip once the screw is set to help with this problem.
Electric screwdrivers are also available, often using the same bits as the power drill adaptors. While they are much slower than a power drill, they are also much less likely to strip the screw head as well.