Many of us do it every day, especially during the winter months.
But we are actually breaking the law and giving someone else an opportunity to commit a crime when we warm our cars up and leave them unattended.
When Dan Luz takes a trip now he has to walk to get there. That's because he made a mistake a few days ago when he stopped at a convenience store near 60th and L.
"I was dumb enough to leave my van running, jumped out of my van went into get donuts," Lutz said. "There's like one or two other cars in the parking lot went in got my donuts paid for the stuff turned around van was gone."
Lutz admits leaving his car running unattended in a public place wasn't one of the smartest things he's ever done, but what Dan, like many of us didn't know, it is also illegal.
"That few seconds leaving it running there unattended, technically it's a violation of the law," Omaha Police Officer Bill Fell said. "We don't really like hitting somebody twice when you report your car stolen and they also get a citation for unattended motor vehicle you don't need to get smacked twice."
Lutz is missing a white 2000 Chevy Astro van with Nebraska license plate SRX-657.
What are his chances of getting his van back?
"I would say its probably better than 50%," Officer Fell said. "The recovery time can be a long time. Many times they're used for a few days and then dumped."
If the van is used in a crime or winds up at the police impound lot it could take months to be released.
"My insurance isn't going to cover it and I cant believe I was dumb enough to leave my car running," Lutz said.
He now pays for his mistake every time he has to take a cold walk, instead of a warm ride.
It is legal to leave your car running if it is parked on private property. Police say the law is intended for those who decide to leave their car running unattended and unlocked while stopping at a public place, such as a convenience store.