Since going on sale in 2006, the Italian motorhome base has dominated the award, coming out on top in all five years.
"We all know that Fiat dominates the motorhome market, and rightly so, because the Ducato offers by far the best combination of price, performance, handling, specification, and different derivatives to suit different motorhoming needs," says Which Motorhome editor Peter Vaughan.
One of the main reasons the Ducato has dominate the award is because of the six-speed Comfort-Matic, automatic transmission.
The transmission comes as an option with the larger three-litre engine, but a 2.3-litre MultiJet diesel is also available.
MultiJet engines have been named International Engine of the Year in the past because of the increase in performance over similar sized diesels along with a reduction in CO2 emissions.
The engines were first seen on the Alfa Romeo MiTo city car early in 2010, where they brought emissions down to 112g/km while offering 95bhp.
The Fiat Ducato is one of the most popular motorhome bases in the UK, and has helped Fiat become a market leader in the supply of the vehicles.
"We are delighted that the award-winning Ducato continues to be recognised as the best base vehicle in one of the most important industry awards around," says Gerry Clarke, director, Fiat Professional UK. "The Ducato range keeps on proving it is first choice among motorhome users, and I’m pleased that these awards have again highlighted the advantages of the new Comfort-Matic gearbox."