The ITM Awards Committee reviewed standards of customer service, vehicle range, aftersales solutions and overall professionalism and reliability.
It found that Subaru UK had made strides in the past 18 months to establish its business credentials in a highly competitive environment.
The institute, which represents 10,000 transport managers and logisticians, said it viewed Subaru as the safest investment opportunity in the car dealership sector.
Subaru provides dealers with the best franchise opportunity
Patrick Sheedy, a director at the ITM, said: “The Institute is delighted to recognise the improvements made by Subaru UK in increasing its dealership profiles and providing dealers with what we believe to be the best franchise opportunity.
“A successfully marketed franchise is always going to thrive and prosper, and this is what is available now to Subaru dealerships.”