AZCentral.com's view

With all the focus on gas/electric hybrid vehicles these $4-a-gallon days, the simple economy of diesel power is largely overlooked.

Seems a shame that U.S. drivers hold diesel in such low regard, aside from pickup drivers. Most people fail to realize that smelly, smoky, rattley diesel engines are relics of the past, that today’s generation of turbo diesels are powerful and refined, and less noxious than their gasoline counterparts.

Jeep Grand Cherokee benefits from Chrysler’s brief association with Mercedes-Benz by offering one of the German giant’s excellent CDI turbo-diesel engines. Since 2007, the midsize SUV has been available with a Benz-designed 3-liter turbo-diesel V-6 that provides the torque of a V-8 with much better fuel mileage and fewer emissions of carbon dioxide.

The engine performs seamlessly, and no one notices a diesel is under the hood. No noise, no smoke, no stink.

As for economy, it pays to do the math. The last time I drove a Grand Cherokee in 2006, it had a gasoline V-6 with scant power and a disappointing 16 miles per gallon. With this diesel version, I got a consistent 21mpg.

Still, a diesel engine, and the fuel it requires, costs more, so let’s do the numbers. Diesel recently averaged $4.68 per gallon in the United States, while regular gas was $4.10. Taking my gas-mileage figures, the diesel would use 48 gallons to go 1,000 miles at a total cost of $223. The gas engine would use 63 gallons, costing $258.

So there you have it, $35 savings for each 1,000 miles. At the national average of 1,000 miles per month, it would take about four years to recoup the cost of the optional diesel engine.

But that doesn’t include the huge performance advantage that the diesel has over the gas engine.

Jeep Cherokee Limited

Vehicle type: Five-passenger, four-door SUV, four-wheel drive.

Engine: 3-liter turbo-diesel V-6, 215 horsepower at 3,800 rpm, 376 pounds-feet of torque at 1,600 rpm.

Transmission: Five-speed automatic.

Wheelbase: 109.5 inches.

Overall length: 186.7 inches.

Curb weight: 4,738 pounds.

EPA rating: 17 city, 22 highway.

HIGHS: Engine performance, improved fuel mileage, updated styling.

LOWS: Jiggly ride, some chintzy interior bits, too heavy.

PERFORMANCE: Though 215 horsepower may sound like a paltry number, the diesel also churns out a hard-charging 376 pound-feet of torque, enough to pull this 4,700-pound heavyweight like a high-performance muscle car while the engine loafs along at low rpm. Really.

That strong torque comes on at a low 1,600 rpm, so it’s always ready to go.

The smaller Jeep Liberty offered a diesel until 2006, but it was a limp inline-4 without much to recommend it. The new V-6 is a whole different trip that should make a diesel believer out of any driver.

Fuel mileage is good, but it could be better. Grand Cherokee needs to go on a weight-reduction program to take full advantage of the fuel economy.

Highway mileage would benefit from a taller top gear to lower high-speed cruising rpm. The engine cranks too high at 65.

DRIVABILITY: Grand Cherokee drives like a Jeep, which is trucklike and jittery on all but the smoothest roads. It has to do with its off-road capabilities that require a compromise in ride quality. I find it acceptable, but some people wouldn’t.

STYLING: A minor upgrade for 2008, mainly to front-end styling, adds refinement to Grand Cherokee’s overall look.

INTERIOR: Though somewhat upgraded, the dashboard and console still feel cheap, with too much hard plastic and chintzy trim. The front seats are roomy and comfortable, a bit less so in back.

BOTTOM LINE: Grand Cherokee and Mercedes M-Class are the only SUVs available with diesel. There should be more.

Base price: $38,555.

Price as tested: $41,055.

OPTIONS

The Limited model is the top, fully optioned version with a collection of comfort and convenience features, such as power sunroof; remote starting; power seats, mirrors and windows; leather; satellite radio, trip computer and premium sound system.

Turbo-diesel engine, $1,655.

Metallic paint, $150.

Shipping, $695.