Automotive Linear Actuator?

Hello everyone. Im new to this world of electronics so please bare with me.

I have an old Volkswagon im building and have some ideas to make it truely 'unique'. My initial idea is to make my own engine monitoring system, but then all kinds of other crazy ideas, like aircraft style speed brakes/spoilers to assist in braking during highway speeds to reduce wear on my brake pads. anyway... my question is this...

to extend and retract a panel, what kind of linear actuators are available? if anyone could at least point me toward a website that would very useful.
thank you

Google linear actuators
example:
http://www.robotshop.com/actuators.html

Best place for linear actuators…

Linear actuators are expensive. However, in abundance and inexpensive are automotive window regulators that convert rotation to linear motion. You also might be interested it automotive power seat drives for your project. Both options will require more mechanics than a linear actuator. Have you considered pneumatics? - Scotty

Check out TV lift systems, and then you can use this as a basis for your design:

View from inside the car:

Looks like 2 x small linear actuators.