Car rental reservations are up 13% this year compared to last, according to Allianz Partners, with Orlando, Denver and Las Vegas as the top three markets this summer.

Those three cities in the same order were also the top destinations for rental cars last summer, Allianz said.

Allianz posited that Orlando, Denver and Las Vegas top the list because they offer both city life and nearby outdoor activities easily accessed via car.

Rounding out this year's top 10 rental car destinations were, in order, Los Angeles; Portland, Ore.; Honolulu; Boston; Seattle; Kahului, Hawaii; and San Diego.

Allianz said the increased popularity in Portland, Boston and San Diego is likely due to travelers feeling more comfortable in city environments. They knocked Anchorage, Miami and Phoenix out of the top 10.

For the study, Allianz analyzed 27,252 online car rental insurance bookings through partners. Reservations were made for the period of May 27 to Sept. 8.