DAF CF, Mercedes Arocs and Volvo FMX Automatic gearboxes in off-road mode

The Bissinger Steige in southwestern Germany is one of the toughest stretches of roadway for truck drivers. From the town of Bissingen at the foot of Teck Castle, it leads up towards the town of Ochsenwang on the heights of the Swabian Alps mountain range. Trucks on this route have to deal with an elevation difference of 400 meters, rising steeply at a 17-percent incline over a relatively short distance. That's a pretty tough job for a four-axle truck weighing 32 tons.
And it's on this stretch that we put the candidates to their first serious test, with the trucks driving up the barbaric incline in normal road mode and in off-road mode. The aim of the exercise is to find out how the off-road mode differs from the normal automatic mode among the three test vehicles.

The first result of this test is that the demanding route, with its mean hairpin at the very end, posed no significant problems for the trucks in either normal automatic mode or off-road mode. The second and more revealing result is how the vehicles' different characters become apparent in off-road mode.
The reduction of gear changes with off-road mode activated compared to the non-stop shifting in normal road mode, for example, varies between vehicles. The DAF, with its 12-speed AF-Tronic gearbox, shows the most radical difference. It performs only around half as many shifts on incline in off-road mode compared to normal mode. The Mercedes Arocs has more choice with 16 gears. In off-road mode, the number of shifts falls only by around a quarter. The Volvo FMX achieves a similar result with its 12-speed I-Shift gearbox, with gear shifts reduced by around a quarter.