Toyota Motor Corp.'s Aristo sedan was the most popular target for car thieves in Japan last year, according to the results of a survey released Thursday.

Of 15 vehicle models of which more than 1,000 cars each were stolen last year, the Aristo topped the list, with one in every 100 Aristos owned being stolen, compared with one in every 1,000 for other models, the research team said.

Toyota's Land Cruiser and Celsior models were both stolen at a rate of seven per 1,000, according to the survey carried out jointly by government agencies and private groups.

The Aristo and Celsior are both sedans, while the Land Cruiser is a sport utility vehicle.

The team, which included officers from the National Police Agency, also found that immobilizers helped prevent thefts of luxury cars. An immobilizer prevents a car from running without a matching key microchip.

For the Aristo model, cars without immobilizers were stolen at a rate 8.6 times that of those equipped with the antitheft system. The rates for the Land Cruiser and the Celsior models were about three times higher without the device, according to the study.

However, almost 30 percent of the vehicles were stolen with the car keys in them, the study found.