Enterprise is back, in a big way. Not only did Enterprise retake the top overall spot in the J.D. Power and Associates 2012 Rental Car Satisfaction Study, the other two brands in the family, National and Alamo, scored second and third overall. This makes a sweep for Enterprise Holdings.

Last year’s winner, ACE Rent A Car, fell back into the pack with a drop in score — from 793 to 736 — that seems to challenge the efficacy of J.D. Power’s threshold of surveys to make the list. (J.D. Power requires a sample size of 100 usable returns to be ranked in the rental car study.) You can bet none of the larger brands — delivering overwhelmingly more surveys — have swung that wildly year over year.

J.D. Power stands by its minimum sample size. Yet Stuart Greif, vice president and general manager of the global travel and hospitality practice at J.D. Power and Associates, acknowledges the challenge of comparing the very large brands to the smaller ones. “We wind up with ratios comparing apples to oranges,” Greif says.

He makes the point that smaller brands with fewer locations operate differently than larger brands, a parallel being the operations of large airports such as JFK compared to smaller airports such as Hartford-Bradley. As well, the smaller brands are subject to larger point swings because changes in a few locations represent a much greater percentage of their overall operation than is true for larger players.

Greif says that the example of ACE going to the top and then reverting to a more historic level is rare, but it happens from time to time across J.D. Powers’ studies and more likely occurs with smaller brands because of the point above. “However, the key issue is still one of how to consistently repeat performance,” Greif contends.

I have a theory regarding the score drop: ACE has 12 corporate stores, but the great majority of ACE locations are within its affiliate network as independently owned operations. While ACE’s corporate store customer service must be uniformly good, and its affiliates must adhere to certain standards to be on the network, there is inevitably a greater variance in customer service with the affiliates. This year, perhaps the mix of surveys J.D. Power collected shifted toward the affiliate network in a negative way. It’s just a theory.

For future studies J.D. Power may consider dividing the segments by large and small or perhaps by region, Greif says, though nothing has been decided.

But let’s not let this get in the way of Enterprise Holding’s performance. Enterprise Rent-A-Car scored highest in both the business and leisure categories. In the leisure category, Enterprise gained 22 points to overtake the top spot, National gained a whopping 26 points to take second and Alamo gained 14 to land at No. 3. In the business category, Enterprise is followed by National, Hertz, Avis and Alamo.

Congratulations to Enterprise Holdings. Though really, congratulations are owed to the industry as a whole for improving the overall average in customer satisfaction by nine points, from 758 last year to 769 this year.

Initiatives to improve customer service are gaining traction, but the work is never done.

For further insights into the 2012 J.D. Power and Associates Rental Car Satisfaction Study and how to use the results to help break free from the stigma of rental car commoditization, click here.