7.2 Percent Hill Climb (Loaded)
The flat asphalt at Milan Dragway was perfect for testing level acceleration, but a pickup truly earns its keep climbing hills while towing.
There were two ways we could have performed our grade testing. The first was to find a challenging real-world incline, like the Cajon and Grapevine passes near Los Angeles, or the infamous 12-mile, 7 percent ascent to the Eisenhower Tunnel in Colorado. The alternative was to run our tests on the much shorter 7.2 percent hill climb at GM’s Milford Proving Grounds. Each percent is the equivalent of climbing 1 foot in elevation over a 100-foot distance, so we climbed 7.2 feet in elevation for every 100 feet the trucks and trailers traveled.
We chose to conduct our tests at GM’s proving grounds for several reasons. First, we wanted controlled conditions under which we could run repeatable and measurable standardized tests to compare the results of each truck relative to itself and its competitors. Comparative testing on public highways is a crapshoot; there was a high likelihood we’d get stuck behind slower-moving traffic, and finding an exit to turn around and repeat a test could require several miles and lots of time, which we didn't have.
The 7.2 percent grade test was 1,720 feet, or 525 meters, long. That's 400 feet more than a quarter mile, which is 1,320 feet.
All trucks and trailers were completely on the grade and stationary prior to the start of each run. All the tests were performed “brake-to-accelerator,” meaning the foot brake was fully depressed with the right foot, which then lifted and fully depressed the accelerator pedal in one movement. Sufficient distance was provided at the end to slow the rigs down to a safe speed before reaching the top of the hill.
A minimum of three runs were carried out in each truck, with the same driver at wide-open throttle in two-wheel drive. We averaged the times from all of each truck’s runs to determine the best performer.
The Silverado was the fastest pickup up the hill, but only by the slimmest of margins. It was tied with the Tundra through the first 430 feet; the trucks were so closely matched we could have passed our BlackBerries back and forth between them as we raced. The 3.42 ring-and-pinion Silverado finished its run just .14 seconds faster than the Tundra. We chalked up the razor-thin win to the Silverado’s 6.2-liter V-8’s extra displacement and old-school pushrod muscle over the Tundra’s sophisticated overhead-cam engine and 4.30 rear axle.
The Sierra finished .73 seconds off the Silverado and .59 seconds back from the Tundra. The Tundra split the two GM trucks perhaps in part because of the Sierra’s stiffer suspension, though it could also have been normal performance variance between the two virtually identical GM pickups — indicating any truck we test could have just had a bad day.
The 3.92-equipped Dodge Ram did well. It finished only 1.08 seconds behind the Sierra. In fact, it was only a half-second behind the GM and Toyota pickups through the first 430 feet lugging the 6,500-pound sled, but as soon as it shifted into 2nd it lost momentum as the engine lugged against the relatively tall gear. It did beat the Titan, however, which topped the Ram during the level quarter-mile while pulling the trailer.
The biggest surprise was the F-150. We suspected it might repeat its sixth-place finish from the level-ground tests, but instead it earned the fifth spot by edging out the Titan. The F-150’s traction control and tow/haul mode combined to out-finesse and hold peak power longer than the Titan. The Titan’s wheels had significant slip at launch, while the F-150’s had less. Some axle-wrap showed up again, like it did during the level-ground unloaded testing, but it was a nuisance that disappeared soon after the F-150 started climbing. Also surprising was that the F-150 continued to coast up the hill — not immediately lose power and momentum — after we let off the accelerator. It’s part of Ford’s new torque converter lockup strategy that cuts off fuel but leaves the torque converter engaged longer to improve fuel economy.