In both runs the GM truck beat the Ford up the hill. The Ford could get a better launch but by about half-way up the grade the Chevy caught and passed the Ford. This isn’t to say there was a large gap between the trucks at the finish. There wasn’t. It never grew to more than about a truck length.
I’d chalk GM’s advantage in this sprint to its six-speed transmission. First gear for both trucks is almost identical, 3.10:1 in the Chevy’s Allison gearbox to 3.11:1 in the Ford’s five-speed TorqShift. The Ford had a takeoff advantage but the Duramax reaches 660 lb-ft peak torque at only 1,600 rpm to the Power Stroke’s 650 lb-ft at 2,000 rpm. And in second gear the Allison dramatically rises to 1.81:1 compared to the TorqShift’s 2.22:1. The Silverado used its earlier torque and second gear to brute force its way past the F-250. By third gear they were more evenly matched again - 1.41 in the Allison to 1.55 in the TorqShift - but by then it was too late. Momentum had shifted in favor of the Silverado.
We took the same trucks and also ran them through a coned slalom course designed to let the driver determine which truck they felt more comfortable towing in when executing rapid and tight turns at speeds up to 45-miles per hour. I’d say they both felt just about the same with a slight edge to the Silverado. Remarkable when you consider the platform and suspension differences in both trucks.
The wet skid pad test was to demonstrate and subjectively evaluate differences between the light duty Chevrolet Silverado’s StabiliTrak and Toyota Tundra’s Vehicle Stability Control (VSC) electronic stability control (ESC) systems.
ESC is an increasingly important safety feature for cars and trucks. It works by combining antilock brakes (ABS) with automatic traction controls - like individual or multiple wheel braking and throttle reduction or shutdown, to help drivers avoid a crash in slick conditions. It does this by measuring vehicle speed, steering angle, and target versus actual yaw rates against the slip rate of each wheel relative to the ground passing underneath. If a wheel’s slip rate is approaching the vehicle’s predetermined stability limit, the ESC system can restore stability by decreasing engine output and braking front or rear wheels to reduce the slippage and help maintain control.
ESC is proven too. According to the Insurance Institute for Highway Safety (IIHS), their research shows that ESC reduces the risk of all single-vehicle crashes by more than 40 percent and fatal ones by 56 percent. The federal government’s National Highway Traffic Safety Administration (NHTSA) has mandated that by 2009 55% of all vehicles will have to be equipped with an ESC system and 100% by 2012.
Mike Rizzo, lead engineer for chassis controls at GM, says the automaker has invested over $10 million dollars creating two extreme skid pads to test their ESC solution on. We drove the ‘less aggressive’ basalt tile pad, which has a kinetic (i.e. sliding) friction coefficient, or μ, of .25 to 3 – a surface more slippery than snow. In comparison, rubber tires moving on dry pavement have a μ of about .8. The second traction pad uses ceramic tiles for an even slipperier surface rating of .12.