Actually, you need to be careful with cigarette lighters and/or utility outlet in the vehicle, you MUST READ your manual to see what max draw is. Many of those are made for very low draw, and if you hook a 500-1000w inverter up, you can easily fry your wires. It's almost always best to hook straight to the battery with clamps.
Just with UPS's, generators, etc, it's best to look for an inverter that produces a true sine wave (if running any AC equipment which the fast majority of us are) to ensure it doesn't damage your pumps/powerheads.