Anyone who's ever driven an older car with a four-cylinder engine knows that, economy aside, they aren't the most pleasant of motors.

They are, in many cases, noisy, with the racket getting especially bad when heading up a hill or trying to pass on the highway. Acceleration is often just enough to stay out of trouble. In a few cases, they can be so slow that they are almost dangerous.

But all of that has changed with the four-cylinder engines that have been introduced in the past few years. Chief among those making the change is General Motors. The company has a new four-banger that's a honey -- so quiet that you don't even hear it running once you start the 2.4-liter engine. And acceleration is lively, and downright sporty. And you still get all this and good gas mileage, too -- it's rated at 22 mpg city/33 highway.

I had a chance a few months ago to drive the Chevrolet Malibu with this new four-cylinder engine, and found it to be a joy to drive. It offered everything a V-6 engine does without compromising on the real reason most people buy a car with a four cylinder engine: Gas mileage.

Recently, I moved up the food chain at GM a bit, and road tested Pontiac's sleek G6 four-door sedan with the same engine. In my view, the whole lineup of G6 models are among the most underrated cars on the market, understandable when you consider that they are competing with much more popular, better-known models such as Honda Accord, Toyota Camry, and, of course, the Malibu.

The coupe and convertible versions are nothing short of gorgeous, and the coupe is better looking than many more expensive competitors.

The design of the G6 is based on a car that debuted at the North American International Auto Show a few years ago, to almost unanimous praise.

It was a ground breaking design for Pontiac that marked a departure from some of the unsightly designs of the past.

The G6 looks a lot smaller than it really is, thanks to the proportions and some aerodynamic design elements. Visibility is good, trunk space is generous, and the driving dynamics definitely are on the sporty side.

Inside, you'll see an Audi-like interior with two-tone dash, lots of nice chrome and aluminum fittings, and a logical, well-designed instrument panel. The biggest flaw I found was that the space between the seat and the door is almost too tight for easy access to the power seat button.

I also thought that there was a bit too much hard plastic inside. Chevy's Malibu, a newer design, goes much further on this score, with an interior that looks straight out of an expensive European sedan.

Though Chevy typically ranks just below Pontiac in the pecking order for GM, it's the Chevy model that looks and feels more expensive, especially with the interior.

But in the G6's defense, this is an older design, and I expect plenty of updating and improvements when and (given GM's current situation) if the design is replaced in the next year or two.

Pontiac also needs to think about providing a six-speed automatic instead of a four-speed with this car; shifts would be more efficient and fuel economy even higher if they did so.

Equipment on the G6, by the way, is quite generous, with full-power equipment such as steering, door locks and windows, a touring suspension, OnStar, traction control, air, 60/40 split folding rear seats, tilt/telescope steering wheel, a reasonably attractive set of seats, alloy wheels, traction and stability control and OnStar.

With a few options, our test car listed for about $23,000.

And what about that four? Terrific, and well worth the price of admission. I think you may have a hard time justifying moving up to a V-6 once you drive it; it's clearly the better bargain here. Fuel economy is more than decent, with highway rating approaching 30 miles per gallon.

All in all, if you don't have the G6 on your shopping list these days, I'd suggest you make amends before you head out to pick your next set of wheels.