Acura adds SUV with first turbo engine

Acura's new sport utility vehicle, the 2007 RDX, is a people and cargo hauler with some brains.

The first Acura powered by a turbocharged gasoline engine, the 240-horsepower RDX uses innovative variable air flow to deliver more torque than any other Acura -- 260 foot-pounds at 4,500 rpm. This is despite the fact the engine is only a 2.3-liter four cylinder.

Acura's Super Handling All-Wheel Drive does more than shift power between the RDX's front and rear axles. The electronically controlled system can shift power between right and left wheels on the same axle, too, for better wheel tracking through curves.

And with an additional technology package that's expected to be in 40 percent of RDX models sold, this new SUV includes high-tech voice recognition for some car commands, a 410-watt, surround sound system and real-time traffic updates for more than 30 major U.S. cities.

Just don't expect the RDX to tackle rugged offroad trails. This SUV is designed for light duty -- primarily pavement and dirt lanes.

Only the second SUV from luxury brand Acura, the RDX has a starting manufacturer's suggested retail price, including destination charge, of $33,610.

All RDX vehicles have a standard five-speed automatic transmission with shift-it-yourself Sequential SportShift.

While pricier than any other four-cylinder SUV on the market, the RDX starting price tag is $4,185 less than Acura's only other SUV, the larger MDX, which starts at $37,795 for a 2006 model with V-6.

Pricing also is less than the RDX's major competitor in the entry premium SUV segment, the 2006 BMW X3, which starts at $37,495 with 225-horsepower six-cylinder engine, manual transmission and all-wheel drive.

On the outside, the five-passenger, five-door RDX is sized about the same as the X3. It's 15.1 feet long, or 5.5 inches shorter than the entry SUV at Lexus, the 2007 RX 350, which starts at $38,095.

But the RDX exterior, while clean and pleasant enough, doesn't convey much personality.

It's neither bold nor rich, so it's easy for passersby to ignore or just lump it in with other, more mainstream vehicles.

The RDX, however, is the first Acura to come standard with large and nicely styled 18-inch wheels and tires. They help keep the vehicle from looking completely boring.

Inside, the RDX does much better, thanks to seats that come standard with perforated leather trim, a large display screen in the middle of the dashboard and even paddle shifters on the steering wheel for manually shifting gears.

I appreciated the large and deep center storage area between the front seats. It can hold a purse, a portfolio, even a laptop, and it locks, to boot.

At 5-foot-4, I could pretty much turn and set myself on the side of the driver's seat to get inside. There's no scrambling aboard, yet the view out the front is good and all riders sit up a bit from the pavement.

The RDX doesn't feel like a lumbering SUV. In fact, with ready power supplied across a wide engine rpm range and not a hint of turbo lag, the tester traveled up hills and around mountain curves eagerly.

Actually, I forgot at times that the RDX had a turbo engine under the hood, though there is a turbo gauge in the instrument cluster that shows a driver when turbo boost is being added. The maximum turbo boost pressure is 13.5 pounds per square inch.

The engineering of the RDX engine, done at Acura's parent company Honda Motor Co., is impressive. The four cylinder combines Honda's already well-known intelligent Variable Valve Timing and Lift Electronic Control (i-VTEC) with a variable flow turbocharger that boosts engine response.

It's the first such combination in a gasoline engine, and both the turbo and i-VTEC in the RDX are connected to the engine control unit, so software manages both systems jointly.

Variable flow means airflow into the turbo can be modulated, using a movable flow control valve, and the RDX turbo is maximally positioned at the rear of the engine to allow exhaust gases to go into the turbo chamber.

To reduce wear and tear on turbo parts, Honda engineers placed as many moving parts outside the hot stainless cast iron turbo housing as they could.

But pricey synthetic oil is a must for this engine, and fuel economy is more like what you'd expect from a V-6 than a four cylinder. Specifically, the RDX is rated at 19 miles a gallon in city driving and 24 mpg on the highway, which is on par with other SUVs that have V-6s, including the 2006 Nissan Murano and Suzuki Grand Vitara.

The ride in the RDX is controlled and quite "flat" in the turns and curves for an SUV, with less body motion and weight shift than expected.

This, plus steering tuned with a sports sedan ratio, makes the RDX feel agile.

The front suspension is MacPherson strut, and there's a trailing-arm-type double wishbone in the rear. Stabilizer bars, front and rear, are sizable at 21 and 19 millimeters, respectively.

Safety equipment is all standard, including six air bags, stability control, traction control, tire pressure monitoring system and anti-lock brakes.

With a towing capacity of just 1,500 pounds, the RDX isn't for major-league boat or trailer towing. But a decent amount of "stuff" -- including two bicycles standing upright with front wheels removed -- can fit in the back where there's 60.6 cubic feet of space when rear seats are folded down.