How Warming Up Your Car Could Make You a Target of Theft

— -- Police departments across the country are warning drivers in these cold months of winter to not leave their running cars unattended.

Police refer to the cars as “puffers.” Nearly 45,000 cars stolen in 2014 had keys inside, according to the National Insurance Crime Bureau.

Denver resident Gregory Kehrl had two of his cars stolen in one day last month.

“I came out, started the car and less than 60 seconds” later the car was stolen, Gregory Kehrl, of Denver, Colo., told local ABC station KMGH-TV.

The keys for Kehrl's second car were in the first car when it was stolen. Nearly five hours later, the second car was stolen from the same location.

Both vehicles were located by police two days later, abandoned and locked in two different locations. No arrests have been made, according to police.

In many states, it is illegal to leave a car idling with keys inside, according to the American Transportation Research Institute. Depending on your state and county, that could also mean in your own driveway.

ABC News’ Clayton Sandell drove through the streets of Lakewood with Sgt. Dave Hoover of the Lakewood, Colo., police department last Tuesday. That day, Lakewood police officers spotted dozens of puffers idling in front of homes and stores in 18-degree weather.

“We’ve got people leaving their cars running everywhere,” Hoover told ABC News.

Sgt. Hoover issued a $57 ticket to one driver who left his car running and unattended in front of a convenience store. Nearby, resident Rick Boyer told ABC News his car had just been stolen in front of his home as he prepared to go to work.

“It’s cold. I wanted to sit in a warm car on the way to work,” Boyer said. “[I] go back inside, maybe for four minutes, come outside, car’s gone,” Boyer said.

Police said stolen puffers are often involved in crimes.

“We’ve seen them used in drive-by shootings, burglary cases,” Lakewood Police Chief Kevin Paletta told ABC News. “We’ve even had instances of bank robberies where the suspects were stealing puffers as a way to get to and from the robbery scenes.”