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GMC mid SUVs

The heavy-duty community has known for years what one light-duty manufacturer is just now re-discovering. In-line six-cylinder engines are among the most efficient of engine designs, especially when coupled with advanced features. All truck power is now I-6 — Cat, Cummins, Detroit, International, Mack, Volvo and Mercedes. Now, so are the General Motors mid-size sport-utility vehicles (SUVs). I set out to test the Chevrolet Trailblazer, GMC Envoy and Oldsmobile Bravada, primarily to try the new Vortex 4.2-liter engines. I was not disappointed, either in the engine or the vehicles.

The engine, common to all three brands, has many features found on GM’s performance products, and a few that are even more advanced. Roller cam followers, variable valve timing and coil-on-plug ignition are found on Corvettes. Double overhead camshafts and four-valves-per-cylinder had been reserved for high performance V-8s, the Cadillac Northstar and the Oldsmobile (now Chevrolet) Indy racing engines. All those features are on this truck engine. Power is greater than one net horsepower per cubic inch; 270 ponies from 256 cubic inches. More important for its function as a truck engine, it peaks at 275 pounds per foot of torque, and develops at least 90 percent of peak throughout the useful rpm range. The 4.3-liter V-6 it replaces put out 190 horsepower and 250 pounds per foot. The new engine lets these 4,500-pound vehicles haul more than 1,100 pounds of payload, with 0-60 times consistently in the low nine-second range.

The common chassis is made with hydroformed frame rails. Steel tubes are put in a mold, the ends are closed, and water (at 35,000-psi pressure) presses the tubes into the mold, like forging from the inside out. The result is a precise closed-section rail with outstanding strength and stiffness. The eight cross member frame is electrostatically coated to resist corrosion. Donut-shaped engine mounts are fluid filled to isolate engine vibration, and the body sits on another 12 tuned mountings. Noise, vibration and harshness (NVH) are reduced significantly from previous models.

All three brands are 192 inches long, on 113-inch wheelbases. Rated to 10,000 pounds gross combination weight, they can tow 5,000 pounds or more. All are 6.5 inches longer, 4 inches wider and 5.5 inches taller than their predecessors. They hold 10 cubic feet more cargo; almost 40 cubic feet behind the second row of seats, and more than 80 cubic feet with those seats folded.

While all have the same mechanical foundation, there are significant styling, interior and option differences between the three.

As expected, Chevrolet is the sales volume leader of the group, and has the least pretentious base model. Most features available or standard in the other models are extra cost options on the Trailblazer. For function rather than style and luxury, it has cloth seats, rubber floor mats and basic trim but the Trailblazer LS. It has dual zone (driver and passenger temperature controls) air conditioning, side impact air bags and aluminum 16-inch wheels with 245/70 R tires, all standard.

The LT package features an 8-way power driver’s seat, OnStar and the options of leather seats. The LTZ option has leather seats standard, everything the other packages offer plus 17-inch wheels with 245/65 R tires, CD and cassette players in the AM/FM stereo.

GM’s smooth 4L60E four-speed electronically controlled automatic transmission comes in all models (Chevrolet, GMC and Olds) but for all those who prefer shifting for themselves or who want a lower first gear (3.48 vs. 3.06), there is a five-speed manual available in the Trailblazer.

The GMC Envoy is almost identical mechanically, but shares fewer than 40 percent of its body parts with Chevrolet. It comes in two models, the base SLE and upscale SLT, featuring lots of leather. Both have leather-wrapped steering wheels, but the SLT’s have radio and HVAC controls built-in, at the driver’s fingertips. A two-position memory for the driver’s seat and outside mirrors is only available on the SLT, as is the 275-watt, six-speaker Bose sound system. Heated driver and front passenger seats are standard, but available only in the Envoy SLT. Same with the automatic climate control and rear HVAC controls. The adjustable rear outlets are knee-high, so they can blow hot to the feet, or cold on the torso. Rain-sensing windshield wipers automatically adjust speed according to how wet the windshield is. These are optional only on the SLT. GMCs have available a rear-only, load-leveling air suspension that offers better-ride-damping, better NVH isolation and an air hose long enough to reach all four tires.

The Envoy has 5-mph bumpers and fiberglass underbody shielding that protects the drive train and helps reduce turbulence and wind noise, from 35 to 37 dB to only 30.5 dB in these.

The Oldsmobile Bravada, unfortunately, will not be around after the division is closed. The Bravada features its own distinctive styling and extra-wide 255/60R tires on 17-inch alloy wheels. It’s optional All Wheel Drive is exclusive to Oldsmobile. It’s a two-wheel-drive until wheel-spin is detected. Then, within a quarter of a second, all wheels get power. That’s a lot faster than people can react. Bravada comes in only one trim level, with everything standard except heated seats, memory seats, rain sensitive wipers, electrochromic mirrors, a sun roof, polished wheels and a block heater, all of which, like the Bose sound system, are optional.

Since GM is closing Olds, they have an excellent incentive for purchasers. Until Oct. 1, 2002, you can get a five-year, bumper-to-bumper service contract at no charge. It’s good at any GM dealership in the United States and Canada.

The real question is, “how do they drive?” I found the performance excellent for a mid-size SUV. All delivered more than 20 mpg on the highway and about 16 to 17 around town. They were quite stable, even when loaded in the rear with my usual test load of salt bags. With 20 bags (40 pounds each) behind the second row of seats, the steering felt a bit lighter, but not enough to be bothersome. Tracking, excellent with just people on board, was still very accurate. Going up my favorite 4 percent test hill at 60 mph, the Envoy stayed in top the whole way with two people on board, and maintained speed with one downshift with 800 pounds of salt.

Ride characteristics varied with tire size and suspension. The air suspended Envoy was stable and seemed to track better through S-turns than did the coil-spring Trailblazer, but if I hadn’t driven them within a short period, I probably would not have noticed any difference.

Match the truck to your needs. For hauling, I’d stay with the basic Trailblazer. You may not need the leather and trim, but you won’t give away performance. For occasional work and family transport, it’s hard to beat the Envoy’s balance of luxury and features. And for added luxury, Oldsmobile is the upscale nameplate. If you plan on keeping the SUV for a while, you’ll appreciate the five-year service contract. As they say, “you pays your money and takes your choice.”