I want to buy a car starter for my mom for her birthday, And I want to know are car starters compatible with all cars or are there certain ones for certain cars? If so can someone tell me whats compatible for a 1995 Saturn SL?

I take it you are referring to a remote car starter rather than a starter motor.

For the most part the aftermarket remote car starters are pretty universal when it comes to automatic transmission installations. If you wanting to install one on a car with a manual transmission, there are some systems that are specifically designed for this application. If you want to safely install a remote starter on a manual transmission car, you need a safety switch to prevent the remote starter from attempting to start the car if the car is not in neutral. You can do this with a magnet and a reed switch.

I doubt her '95 Saturn has the GM VATS key system (resistor in the key) but if it does, you'd need to install a VATS bypass kit as well.

-Rod