As we raced the 2010 Acura RDX along winding mountain roads, feeling out corners carefully so as not to send this small SUV tumbling, we wished the turbocharged engine and all-wheel-drive system were in a completely different car. Throw this running gear into a small coupe, ditch the five speed automatic for a slick six-speed manual, and Acura would have an impressive replacement for the discontinued RSX.
But as it is, the 2010 RDX competes in an extremely crowded market, against the likes of the Honda CR-V, the Mitsubishi Outlander, and the Nissan Rogue. Somewhere in Acura headquarters, someone looked at all these other small SUVs, and decided to jump on the bandwagon, going for mass-market popularity as opposed to a niche sports car. But the power train engineers seemed to be building a different car, and were probably surprised to see their engine sitting between the high front wheels of an SUV.
That engine and the all-wheel-drive system, and to some extent the automatic transmission, make the 2010 RDX one of the sportiest drivers amongst small SUVs, but the turbocharged engine doesn't do well with the car's near-2-ton curb weight. A V-6 would have given it smoother acceleration and probably delivered better fuel economy.
The power train is comprised of a 2.3-liter four-cylinder engine with Honda/Acura's i-VTEC technology, controlling valve timing and lift, a variable flow turbocharger with a peak pressure of 13.5 psi, and a five-speed automatic that includes sport and manual shift modes. The turbocharged engine puts out 240 horsepower at 6,000rpm and 260 pound-feet of torque at 4,500rpm.
Although Acura claims its variable-flow turbocharger minimizes lag, we beg to differ. The gas engine gives the RDX adequate push from a stop, and then the turbo kicks in when the engine hits about 2,500rpm. At that moment, a very perceptible power boost hits the RDX, giving it uneven acceleration. During passing maneuvers, attempting acceleration at speed, the turbo's late kick made it difficult to judge safe distances. The turbo lag is not as extreme as with the Subaru WRX STI, but it is definitely there.
In general, a turbo is a good way to increase power without negatively affecting fuel economy as much as more displacement would. But that equation doesn't work out so well in the RDX. EPA fuel economy is 17 mpg city and 22 mpg highway, pretty dismal numbers for a four-cylinder engine. In our mixed freeway, mountain highway, and city driving, we achieved an average of just 18.3 mpg. The bigger Lexus RX 350, with its 3.5-liter V-6, got better fuel economy.
Of course, that Lexus also has a six-speed transmission, versus the five-speed automatic in the RDX, which will affect fuel economy. We would have preferred an extra gear in the RDX transmission, but we were impressed with its capabilities. In manual mode, it changed gears quickly every time we pulled one of the paddle shifters on the steering wheel, without a lot of the torque converter slushiness that usually comes with automatics. Its sport mode kept the engine speed high, but didn't downshift aggressively as we braked before a corner.
Our RDX came with Acura's Super Handling All Wheel Drive system (SH-AWD); a front wheel drive RDX is also available. This system holds the road incredibly well. As we dashed over wet roads on a drizzly day, we could feel the system work to keep the RDX on the pavement, especially in the corners as we put more and more speed on. Working against it was the car's high center of gravity, hence our wish for a low-slung sports coupe that could really take advantage of this technology. SH-AWD not only transfers torque dynamically from front to rear; it also sends it between the two rear wheels as needed. A neat little torque graphic on the instrument cluster shows second-by-second torque distribution, but you can't really monitor it when performing maneuvers that make it change.
The cabin of the 2010 RDX doesn't feel particularly luxurious, although it looks nicer than a typical economy car. There are hard plastics, but Acura finishes them well. The buttonitis affecting many Acura models is kept in check on the stack, but still overwhelms the steering wheel.