Audio capacitors are not intended to start a car up. THey have very low capacity and are meant for power regulation for amplifiers. A dead battery will drain your cap very quickly.

Wiring a 12 volt cap in series with a 12 volt battery will yield 24 volts, DONT DO IT. It will fry many things in your car. You will need to wire it in parallel. Positive terminals together and negative terminals together. THis will keep the voltage the same and multiply the amperage.

You will want to run your cap as close to your amplifier as possible.

Caps also introduce a 1 volts drop across the top of it. Running a capacitor in your car could lower your total voltage. You might want to do some more research about the pro's and cons of using capacitors. Try www.termpro.com forums.

I'm personally against caps and would rather have an extra battery.