If you want to be treated well at a car dealership, buy a Mercedes-Benz or a Lexus. That's the conclusion reached by researchers based on a new study that looked at how various dealerships treated potential car shoppers.

Reuters reports, "Daimler AG's Mercedes and Toyota Motor Co's luxury Lexus brand topped a ranking intended to measure how well U.S. car shoppers were treated in dealer showrooms whether they bought a new car or not." The study, conducted by the sales consultancy firm Pied Piper, sent paid researchers into dealerships posing as car shoppers, and asked them to rate the dealerships on qualities that actual car shoppers had ranked as being important to them in an earlier study.

Motor Trend adds, "Study author Fran O'Hagan says up to 90% of car shoppers walk out of dealerships -- as opposed to driving out with a new car -- and stresses the importance of a satisfactory shopping experience."

Four of the five top-scoring brands were luxury makes, with Jaguar and Land Rover joining Lexus and Mercedes near the top of the list. The only builder of affordable cars to score in the top five? Saturn - which General Motors plans to sell as part of its recovery from bankruptcy.

There was good news for GM in the survey, however. Motor Trend notes, "Three of the four brands General Motors is keeping -- Cadillac, Chevrolet, and GMC -- scored above average. Pontiac, Saab, and Hummer" - all brands GM plans to sell or discontinue - "fell below."

What dealerships might you want to avoid if the buying experience matters to you? Reuters notes, "The lowest-ranked dealerships by brand were Mitsubishi Motors Corp, Pontiac, Saab, Jeep and Chrysler," while "BMW's Mini, Toyota's Scion and Smart, a joint-venture between Penske and Daimler," also scored below average.

If you're in the market for a new car, check out the U.S. News rankings of this year's best cars as well as this month's best car deals.