Portland saw a sharp spike in car thefts in 2011. The culprit? Complacency.

Most of the cars stolen had the keys in them or were left running when they were taken, police said. Most were recovered within a few days not far from where they were taken.

“More often than not, we find them after they’ve been issued parking tickets or towed,” said Lt. Gary Rogers, head of detectives for the Portland police.

The number of stolen cars jumped from 58 in 2010 to 91 in 2011, a 63 percent increase. The rise seems to run counter to national statistics, which showed a drop over the first half of 2011 by 5 percent over the same period in 2010, according to data from the Insurance Information Institute. Car thefts nationally have gone down each year since 2003.

Portland reports its car thefts to the state and the FBI, but most do not end up being classified by the department as motor vehicle theft, which is a felony. That’s because most of the cars are quickly recovered and therefore the charge — when a culprit is found — is unauthorized use of a motor vehicle, a misdemeanor.

Portland police solved about 27 percent of car theft cases, which beats the national average of 12 percent.

Most car thefts fall into one of three categories:

* The car is loaned to somebody who does not return it.

* The car is taken from a convenience store, gas station or fast food restaurant when someone leaves it running.

* A car burglar finds the keys in the ignition, or in the glove box, ashtray or the compartment between the seats.

“When motor vehicle burglars are going through cars looking for iPods and GPSs, when they stumble across a set of keys, they use the car to transport the booty across town,” said Det. Barry Cushman, who investigates many of the car thefts.

Cushman said only a handful of the cars stolen in 2011 have not been recovered.

Cushman said sometimes a car is stolen for a purpose. For instance, he recalls one case in which a car was broken into and the ignition forced. Police believe the thieves were stealing a spool of copper wire and needed a bigger vehicle to transport it. They forced the ignition of a van and removed the seats. The van was recovered in Windham a few days later.

Michael Barry, spokesman for the Insurance Information Institute, said the rise in auto theft in Portland probably won’t translate into higher insurance premiums because rates are based on claims. If cars are recovered intact, the owner doesn’t need to file a claim, so rates aren’t affected, he said.

In other areas where car theft is a major problem, the cars often end up in “chop shops,” where they are stripped and the parts sold on the black market, he said.

Barry also noted that even though car thefts jumped last year, the number of thefts in Portland is lower than comparably sized cities.

Maine historically has one of the lowest rates of car theft per capita, with 76 cars per 100,000 people stolen in 2010. The national average was 239 and in one of the worst areas of the country, California, 413 cars per 100,000 people were stolen.

In Portland, with a little more than 64,000 people, the rate went up to 141 cars stolen per 100,000 people last year.

Barry said the notion that people might leave their cars running while they went into a store is unheard of in New York, where the institute is based.

“The idea of seeing a vehicle idling with no one in it, I think people would probably report it as a suspicious vehicle rather than get in it,” Barry said. “I think the reaction in Manhattan would be to run away rather than run toward it.”

For victims of car theft, the impact can be costly and inconvenient even if they get the car back.

Sara Deane, manager of Standard Baking Co. on Commercial Street, said the shop was broken into Christmas Day and the thief took the bakery’s van and used it to cart away other loot.

The bakery rented a van to make its early morning deliveries until the stolen van was found a week later a few blocks away. The bakery had to pay for the rental, a tow, a jump start and hire a mechanic to look for any damage to the van, in which a new engine was installed the day before it was stolen.

It wasn’t the money that was the chief concern.

“It’s more of a pain in the neck,” Deane said.