Technology-laden vehicles present a double-edged sword for rental car companies, according to a new J.D. Power study. Rental car satisfaction scores are highest when vehicles have 21 or more features, such as cruise control, GPS, UBS ports and premium sound systems.

But those scores fall 140 points when renters say that vehicle features are difficult to use.

That is one finding of the J.D. Power 2019 North America Rental Car Satisfaction Study, released on Wednesday.

Hertz ranked highest in overall satisfaction.

The study notes that as airport-based rental car companies see increased competition in all areas. They have “doubled-down on innovation,” according to the study. Those companies now offer more vehicle choices, personalized service and streamlined pick-up and return processes.

And that innovation is resonating with customers, J.D. Power said.

An additional finding of the study is that overall rental car satisfaction is at its highest level ever, and the gap in performance between the top- and bottom-ranked performers has narrowed to just 31 points. That is down from 51 points in 2018. Now, just one point separates the top two companies in the study.

A key differentiator: A smooth pick-up process. That area shows significant variation in customer experience. Overall satisfaction scores are 33 points higher when customers get their vehicle in 15 minutes or less, but that happens just 64% of the time.

Another key finding: Mobile app users more satisfied with the rental experience.

Among customers who use a rental car brand's mobile app, overall satisfaction is 50 points higher than among those who do not.

Only 40% of customers currently say they have a rental car mobile app downloaded on their smartphone. How are rental car apps used? Most frequent use is for making reservations, getting shuttle information, getting general information, check-in, and selecting the rental car.

"Across all of our travel-related studies, rental cars have become the most satisfying part of the overall traveler experience," said Michael Taylor, travel intelligence Lead at J.D. Power. "This is due largely to companies' continued innovation to tweak their pick-up and return processes and deliver stand-out customer experiences. Many customers can walk the lot and pick a specific car, and the pick-up process can be completed in 15 minutes or less.

"Adding personalization through apps and alerts to mobile devices is a big plus, too," Taylor went on to say.

J.D. Power 2019 North America Rental Car Satisfaction Study

(Based on a 1,000-point scale)

— Hertz: 856

— Enterprise: 855

— Alamo: 848

— National: 843

— Industry Average: 843

— Avis: 833

— Thrifty: 831

— Dollar: 826

— Budget: 825