September 11, 2007

Comparison Test - GM's new pickups: how do they compare?

2007 GMC Sierra HD; photo courtesy GM Canada. Click image to enlarge

By Chris Chase

Photo Gallery: General Motors Trucks Challenge

Blainville, Quebec - For automotive journalists, getting a chance to drive a vehicle back-to-back with its direct competitors is pretty rare. Usually, the easiest way for us to do so is the same way you would: visit the appropriate dealerships to test-drive them.

So when General Motors invited journalists to the PMG Test and Research Centre to drive its new full-size pickups and them compare them to popular competitors - well, we just couldn't say no.

That's how I ended up at PMG, located just north of Montreal, at what GM called the Silverado/Sierra challenge, where the new-for-2007 Chevy Silverado and GMC Sierra were to be pitted against the Ford F-150, Dodge Ram and Toyota Tundra in a series of tests designed to gauge the trucks' off-road capabilities, stability control systems, a towing exercise (here, we got to sample GM's even newer diesel-powered heavy-duty pickups), and in a final event that allowed us to compare the trucks in terms of acceleration, braking and handling.

Now, keep in mind that an event like this, as organized by a manufacturer, is going to be designed to show off the strengths of that company's products. So, with the bias-o-meter at the ready to keep things as objective as possible, I took the wheel to see what these GM trucks can do that their competition can't.

2007 Toyota Tundra (top) and GMC Sierra; photos by Chris Chase and Russell Purcell. Click image to enlarge

First up was the off-road traction test. The trucks were left in rear-wheel drive only, and with one rear wheel placed on a set of rollers, the object was to see if the trucks' traction control systems could divert enough torque to the rear wheel with traction to get the truck over a rubber block placed in front of a front wheel. Then, each truck was driven up onto a set of ramps meant to render two opposite wheels with little to no grip.

Here, a GMC Sierra fitted with an optional locking rear differential - it's available on just about any new-generation Chevy Silverado or GMC Sierra - was the only one to succeed in both tests, while the others had to resort to four-wheel drive or, in the case of the Ford, going back the way it came.

For the towing demonstration, GM had brought along trailers loaded up with 7,000 pounds worth of ballast, which were hitched up to a Dodge Ram with the 5.7-litre HEMI V8, a Ford F-150 with a 5.4-litre engine, a Toyota Tundra with its 5.7-litre V8 and a Silverado with a 5.3-litre V8. This match-up meant the Chevy actually had the least amount of torque of the four trucks, and it felt that way.

2007 GMC Sierra HD (top) and Chevrolet Silverado; photos courtesy of General Motors Canada. Click image to enlarge

GM also brought along a Silverado with an optional VortecMax 6.0-litre V8 (the package brings a bunch of heavier-duty chassis and drivetrain bits, too), which gave the Chev an advantage. While low-end power was only a little better than the 5.3-litre, the 6.0-litre has far better high-end pull and felt stronger at high revs than the other three trucks' engines did.

On a driving course that simulated highway driving (with the trailers still hitched up), the light-duty Silverados felt better planted at high speed, requiring fewer small steering inputs to stay on course than the other three did.

It was here that we got to sample GM's new heavy-duty pickup, too, back-to-back with the Ford F-series Super Duty. Neither had any trouble towing 12,000 pounds, but the diesel engine in the GM felt smoother, particularly at idle, where it was tough to tell the 6.6-litre V8 was a diesel at all. GM didn't bring a heavy duty Dodge Ram along as Dodge recommends using a fifth-wheel hitch for towing more than 10,000 pounds.

Next, a large section of the paved infield was watered down to create a slick surface to allow us to test the trucks' stability control systems. Of the four trucks tested here, only two had it: it's standard on crew cab versions of the GM trucks and the Tundra, but optional on the Ford and Dodge in our group of trucks. As a result, this part of the day was really a two-truck comparison.

2007 Chevrolet Silverado on the wet skidpad; photo by Russell Purcell. Click image to enlarge

This test revealed how differently each manufacturer approaches this technology. Throw the Tundra around and the Toyota stability control system intervenes abruptly to steer the truck where it thinks you should be going.

GM's system is far more transparent in its operation, working to make the truck go where the driver points it. It feels far more sophisticated (for all that throwing a full-size pickup around an empty parking lot can be), and as effective as the Toyota system is, the GM setup is more confidence-inspiring thanks to its smoother interventions.

The last test we conducted involved driving the trucks through a cone course that incorporated slalom sections to test handling and responsiveness, and straight bits for testing standing-start acceleration and panic stop performance.

As in the towing challenge, two different GM trucks were provided: one a "regular" crew cab model and the other a leather-lined Sierra Denali version. Of these two, the Denali, with its lower-profile tires, lower ride height and firmer suspension, proved the better handler. Naturally, none of these trucks handled the slalom like a sports car, but the GM trucks - both here and in the towing test - were the easiest to drive, exhibiting a more car-like character than the others. That ease of use was something I noticed when I test-drove a Sierra crew cab recently.

The trucks being compared; photo courtesy of GM Canada. Click image to enlarge

In acceleration tests, the Sierra Denali was the quickest, with its 6.2-litre V8 making 400 horsepower and 415 lb-ft of torque. Of the other four, the Tundra felt fastest in a straight line, while the regular-grade GM and Dodge all felt similarly quick, with the Ford bringing up the rear.

Straight-line braking distances, for the most part, were similar between the two GMs, the Toyota and Ford. The Dodge was the big loser, though: with only rear-wheel anti-lock brakes, the Ram's front wheels locked up in hard braking, flat-spotting the front tires. The result, as described by another tester, was like driving around on those old-style 12-sided nickels. The Ford's stopping distance was a little longer than the others, too, due, perhaps, to a suspension that felt softer than the GM trucks' and Toyota's.

So while this was a useful - if biased - comparison, it's a kind of preview of what will go down later this month at the second-annual Truck King Challenge. That's where organizer Howard Elmer will bring together trucks of all sizes near Peterborough, Ontario to compare them in a more objective manner.

In last year's event, the last-generation Toyota Tundra and 2007 Dodge Ram took home honours in the half-ton full-size V8 categories, so it will be particularly interesting to see how the redesigned Tundra and GM trucks compare to older designs like that Ram and Ford's F-series. Watch this space for results in a few weeks.

Related articles on CanadianDriver

• CanadianDriver's Focus on Trucks
• Feature: 2007 Truck King Challenge

Manufacturer's Web site

• General Motors Canada

Chris Chase is an Ottawa-based automotive journalist.