Boat U.S. - January 2008 - (Page 24) Another 42-state offering, the Volkswagen Touareg, is available with a V10 TDI diesel power plant. The VW V10 engine produces 310 hp and 553 lb.-ft. of torque, giving the Touareg a towing capacity of 7,716 pounds while still providing 15 mpg city, 20 mpg highway. If 7,000-plus pounds of towing capacity just isn’t enough for you because your load weighs up in the five-digit range, the heavyduty pickup offerings from Chevrolet, Dodge and Ford are the answer. These vehicles have towing capacities starting at 10,000 pounds and climbing past 15,000 with proper equipment. And each manufacturer has mated these big pickups to an equally big diesel. Chevy’s diesel power plant, the 6.6liter Duramax, pumps out a class-leading 365 hp and 660 lb.-ft. of torque. Available in Silverado 2500HD and 3500HD pickups and mated to an Allison six-speed transmission, various configurations of the Silverado can tow between 10,000 and 16,500 pounds. An available integrated electronic braking controller allows the truck’s ABS braking system to work in conjunction with the trailer’s brakes, helping to keep the whole rig from locking up. The Duramax is a 50-state engine. The Duramax engine is also compatible with biodiesel blends of up to 5%, called B5. But these workhorse trucks are not just for the construction site anymore. Chevy offers the same luxury interiors found in its SUVs, complete with leather and wood grain accents, in these new Silverado HDs, including an optional sunroof. “The most common thing I hear about diesels today is that people don’t know they’re in a diesel truck anymore,” says Brian Maki, Silverado marketing manager. “You aren’t spewing black smoke when you’re on the accelerator.” It’s a familiar refrain echoed by other automakers. “Most of the general population either have no experience with diesel power or the wrong experience,” says Dan Bodene, spokesman for the Dodge Ram pickup lineup. “Most folks haven’t been exposed to modern diesels which are fantastic power plants.’” The Dodge Ram 2500 and 3500 HD models are available with a Cummins 6.7liter engine that puts out 350hp at 3,000 Photo courtesy of Chrylser Corp. Light-duty diesels like this one from Chrysler will be more common in mid-sized SUVs and pickups in the coming model years. Hybrids That Can Handle the Load The 2008 Chevy Tahoe Hybrid features a new, two-mode hybrid motor linked to a 6-liter V8 that gets 25% better fuel economy and still is rated to tow 6,000 pounds. The hybrid Tahoe was recently named the 2008 Green Car of the Year, by Green Car Journal. The Journal cited the hybrid Tahoe’s 21-mpg city rating, a 50% improvement over the conventional power train in city driving conditions, which remarkably, is the same rating achieved by a four-cylinder Toyota Camry. This two-mode system offers the flexibility of an all-electric mode for stop-and-go driving, with a power boost mode for high demands, saving fuel in the city and on the highway. GM coupled this hybrid technology with the ability to “turn off” four of the eight cylinders when cruising without high loads. Often referred to as displacement on demand, and now called Active Fuel Management, this system allows an engine of significant displacement to act like a much smaller engine when high power is not necessary, but still have all that power available when it is, such as when towing. GM developed the two-mode hybrid in conjunction with Chrysler, which announced at the Los Angeles Auto Show the debut of hybrid versions of the Dodge Durango and the Chrysler Aspen. GM also revealed its hybrid version of the Silverado. rpm and 650 lb.-ft. of torque at just 1,500 rpm. “These diesels will pull your house right off its foundation,” says Bodene. The various towing packages available start at 12,100 pounds of towing capacity and climb all the way to 16,800 pounds. One of the innovations that comes standard with the Cummins diesel especially for towing heavy loads: exhaust braking. An exhaust brake takes advantage of the fact that diesel blocks are built to handle high compression. By restricting the escape of exhaust gases after the power stroke, compression builds at a point where normally the piston would be pushing all the exhaust gases out freely. The restricted flow of exhaust slows the piston and the engine slows as well. All of this is computer controlled according to brake input from the driver and kicks in automatically if necessary to assist in a sudden stop or on a steep grade. Of course these big diesels provide a fuel economy advantage as well, but precise numbers aren’t available. The EPA does not rate the fuel economy of vehicles with a gross vehicle weight rating of more than 8,500 pounds. All of these HD pickups exceed that number. But road testing conducted for Diesel Power Magazine confirms better fuel numbers. And so did Cappa saying, “Even if they made a big-block gas engine that had the same power and torque, which they don’t, you would still have 30% better overall fuel economy.” All of which add up to an attractive “alternative” engine technology that you can buy now. — By Michael Vatalaro 24 BoatU.S. Magazine January 2008
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