Lexus came top in 12 of the 15 categories and was second in the other three.
Overall Lexus beat Porsche, sister brand Toyota and BMW in the league table.
Also, Fiat is among the most improved motor industry franchises in the country, according to the survey.
Following some successes registered in last year’s Sewells survey, Fiat Auto’s performance in the eyes of its UK dealer network has improved in the last 12 months; the company moving up nine places in the manufacturers’ ‘league table’ – the third highest movement overall – and posting an overall score which makes it the second most improved franchise in the survey.
In fact, dealer perception of Fiat as a motor industry franchise improved in 16 of the 17 sections surveyed – and the Italian company is now widely regarded as one of the most profitable franchises, and one with which existing partners are keen to expand.
The latest Sewells DAS is the fourth successive survey of this type in which Fiat has been seen to be improving its performance.
The annual survey asks UK dealers to judge the carmakers on various aspects of the business, including supply of cars and parts, warranty and marketing.