By Jim Kerr
What do the Hyundai Veracruz, the Ford Edge and the GMC Acadia have in common? They all are powered by a V6 engine, come with six-speed automatic transaxles, and are either offered or come standard with all-wheel drive. These crossover vehicles offer a smoother, passenger car-like ride than typical SUVs without losing the SUV’s utility. This V6, six-speed and AWD powertrain configuration can be found in other crossover utility vehicles too, so why has it become so popular?
First the engines: all three vehicles have engines ranging from 3.5 litres to 3.8 litres. This may seem a small displacement to power these larger mid-size vehicles, but the use of variable camshaft timing and double overhead camshafts enables these smaller engines to produce torque over a broad rpm band. Think of torque as pulling power. The power enables these vehicles to accelerate snappily away from a stop or pass another vehicle on the highway in short order.
The small engine size has another advantage: good fuel economy. The larger the engine, the more fuel it will consume if it is installed in the same vehicle. True, a smaller four-cylinder engine would be able to achieve better fuel economy under some driving conditions, but it would have to work harder and could use even more fuel when heavier acceleration or pulling loads are placed on the engine. The V6 is a good compromise between power and economy.
The six-speed automatic transmission works well with the smaller displacement V6 engines. First gear is a lower ratio than found in four-speed and even five-speed automatics. This low gear ratio multiplies the torque more for quick off-the-line acceleration, or more power pulling that boat out of the water at the boat launch. The six-speed automatic also has taller top gears. Fifth and sixth are overdrive gears, decreasing engine rpm during highway driving. This reduces engine noise, wear and improves fuel economy. Another advantage of the six-speed automatic is that the steps between gears are small, keeping the engine in the optimum rpm range for best performance.
Ford Edge (top) and GMC Acadia. Click image to enlarge
I remember when most automatic transmissions were two speed units. They needed big displacement V8 engines with lots of torque to overcome the disadvantages of only two gears. That was why four-speed manual transmissions became so popular in many performance cars. Now the technology has reversed that situation, where automatics provide more gears than manual transmissions and also provide more performance. Mercedes offers seven-speed automatics on some of their vehicles, and Lexus even has an eight-speed automatic on their LX460 sedans. The six-speed automatics seem to be the best choice between economy of manufacturing and vehicle performance. That is what is making their use so popular.
Finally, these vehicles use front-wheel drive with an all-wheel drive rear axle to provide both fuel economy and all surface traction. During most driving situations, the torque is applied through the front drive wheels. The rear axle is just along for the ride. When additional traction is required, the rear axle is engaged with computer-controlled clutches. This layout eliminates the parasitic drag of four-wheel drive systems on hard road surfaces, yet can instantly switch to four-wheel traction during acceleration or on slippery surfaces. The increased traction provides better balanced handling on corners and improves vehicle safety by giving the driver better control.
Hyundai’s Veracruz has the luxury CUV buyer clearly in mind. The Ford Edge is priced lower and will be more attractive to families, while the GMC Acadia takes a middle ground, with more aggressive SUV styling. Even though each is aimed at a slightly different market, it is interesting to see that their powertrains, although coming from different engineers and designers, have arrived at the same time and place with a lot in common. Imitation truly is a form of flattery.