Hardwiring / powering a arduino through a car

Hey I'm stuck on a project of mine. I'm trying to build a turbo timer but I want to power it through the cars battery terminals or battery it's self. I prefer placing everything under the steering wheel panel and run a wire to ground and positive to a terminal instead of running it through the fire wall. Anyone can please help me ?!?!?

12V->USB-Adapter. I don't think you know what you are trying to do, though. I feel like you are going to destroy your car and/or hurt people. Also, letting the motor run unnecessarily might be illegal where you live. (In germany, it is)

lg, couka

Lol yeah your right about me not knowing what I'm doing . Thank you for informing me but it's legal here in the states as long as there is a kill switch . But I just want a clean setup hidden away. But I'll just go with the 12v to usb

What's a turbo timer do?

CrossRoads: What's a turbo timer do?

It keeps the engine going in idle for some time after leaving the car, so the turbo charger is able to cool down slowly.

lg, couka