2015 Ford F-150: Downhill Speed Regulation Done Right
February 24, 2015
Last weekend I found myself approaching the same long downgrade that had earlier goaded our 2015 Kia K900 into doing wrong things in an effort to keep its speed in check. But this time I was in our new 2015 Ford F-150 Lariat 4x4 pickup, which presented a perfect opportunity to set the cruise control at the same speed and see if the F-150 could do any better.
Before I reveal how it went, allow me to first set the table. I was alone. I wasn't towing or hauling anything, so there was no need for Tow/Haul mode. And this simple interstate cruise wasn't the appropriate time or place for so the newly added Sport mode, either. This was routine stuff, everyday driving in "D" with the transmission in its normal default mode.
With cruise engaged, the truck approached the grade at the desired 65 mph in sixth gear at about 1,750 rpm. Nothing changed in the first moments of the descent, but as the slope got steeper the truck's speed crept up to 66 mph, then 67 mph.
But that's as far as the situation progressed before the transmission spontaneously dropped into fifth gear. The F-150 didn't gain any more speed from that point on, but as the grade continued to pitch downward the ECU decided another downshift was necessary and the transmission dropped into fourth.
At that point the engine speed stabilized at about 3,000 rpm as the truck's speed was reined in to 65 mph. Equilibrium was restored, and that's exactly how it stayed for the remaining five miles of the grade.
That's how this is supposed to work. Transmission downshifts should be the first line of defense, increasing the engine's speed to provide the necessary engine braking. I'll gladly take the piddling 2-mph overshoot if that's what it takes for the ECU to recognize the circumstances and respond in a measured way that keeps the brakes out of it.
It's not surprising that a pickup truck would have this sort of thing figured out. The engineers involved know full well how towed weight or a heavy payload can exacerbate this sort of situation on steep hills, and they also know that gearing down is the safest and surest way to control speed.
But this was just one grade. Another staffer drove a different 2015 F-150 with the same 2.7-liter Ecoboost engine (a pre-production sample, admittedly) on a different downgrade at a different speed and was not nearly as impressed. And we've yet to try this with a trailer pushing from behind.
Still, as the saying goes, so far, so good.
Dan Edmunds, Director of Vehicle Testing @ 1,373 miles