I WAS SITTING

in the typical traffic crawl approaching the George Washington Bridge when a guy with big hair in the next lane started honking incessantly. Had I accidentally cut him off? Had my "Red States" baseball cap struck a nerve? With trepidation, I lowered my window.

The guy flashed a smile as big as his hairdo and gave me an emphatic "thumbs up" sign. "Nice car!" he shouted.

The car was the new Jaguar XK, tested by SmartMoney along with a trio of other luxury coupes: the Mercedes-Benz CLS500, the BMW 650i and the Lexus SC 430. Each of these comes with a pedigree nameplate and a price tag between $65,000 and $75,000.

But this contest wasn't even close: The XK won handily despite the tough competition. Even in a traffic jam, the XK looks fast. And while not the highest in horsepower, it feels quicker, more lithe and more agile than the others in short, just what a Jaguar should feel like. Jaguar's excellent showing in the latest J.D. Power quality survey cinched the SmartMoney Award for the XK. Here's a look at how all four luxury coupes shape up.

2006 Mercedes-Benz CLS500 Coupe
The CLS500 has the largest backseat among these cars because it's the only "four-door coupe," as Mercedes states, in the bunch. It's also the only car here with a seven-speed automatic transmission; the others have six speeds. The swept-back styling is attractive, though not head-turning.

At $65,675 (all prices include destination charge), the CLS500 has the lowest sticker price. However, the CLS500 is the only one of these contenders in which the in-dash navigation system is optional, not standard.

Moreover, the CLS500 isn't much fun to drive. The 302-horsepower, 24-valve V-8 engine is adequate and produces respectable gas mileage 16 mpg in the city and 22 on the highway. (Every car here requires premium gas.) But at 4,050 pounds, the CLS500 is the heaviest of these four cars, damping some of the fun.

2006 Lexus SC 430 At $66,050, the Lexus is the second-least-expensive of these cars. The curvaceous styling is attractive, though it's several years old and doesn't grab attention anymore.The SC's defining feature is its marvelous retractable hardtop, making it the only standard convertible car of this group. But when the top is retracted, it fills up most of the car's trunk.

I tried putting a short adult in the tiny backseat, and he had to sit sideways. Also, the cupholders won't hold securely anything that's tall, such as a water bottle.

The 288-hp V-8 is the least-powerful engine of the group, while the SC is the second-heaviest of these cars. Gas mileage is 19 city, 25 highway, and zero-to-60 time is 5.8 seconds. But like the CLS500, the SC doesn't feel very quick.

2006 BMW 650i
The 650i delivers BMW's hallmark: performance. Handling is crisp and precise. The V-8 packs 360 hp, more than any other car in this bunch. And the 650i is the only one of these to offer a manual transmission, which, like its automatic cousin, sports six speeds. The automatic performs best in "sport mode" setting.

The 650i coupe gets a group-best zero-to-60 of 5.3 seconds with the manual transmission. (The convertible is slower at 5.6 seconds because it's heavier.) The coupe's gas mileage with automatic transmission is 17 city, 25 highway slightly better than with the manual. BMW can tune the automatic for better mileage than with manual shifting.

Buyers of the 650i get two complimentary days at the BMW Performance Driving School in South Carolina. Ideally, the instruction would cover using the "iDrive" mouse-like device to control the audio, air-conditioning, heating and navigation. This iDrive is better than the first version, but still needlessly complicated.

At $72,495 for the coupe and $79,495 for the convertible, the 650i is the second-priciest car here.

2007 Jaguar XK

2007 Jaguar XK

Base Price: $75,500 (includes destination charge)

Engine: 4.2-liter V-8, 300hp

Ride/Handling:

Int./Ext. Design:

Comfort/Utility:

Overall Rating:

I was surprised by how much I liked this car. The styling is superb. The interior is comfortable, with convenient, user-friendly dashboard controls, great cupholders and just-right proportions. The trunk is a decent size, about 11 cubic feet.

While the coupe's zero-to-60 time of 5.9 seconds is "slow" for this group, the XK feels quick and is the most fun to drive, hands down. That's partly because the XK is the lightest among these cars.

The "smart key" system features push-button starting and stopping whenever the key fob is anywhere in the car even in your pocket. But it would be handy to have a slot in which to insert the key fob, just to keep track of it.

That aside, though, the XK is great, and the clear winner among these luxury coupes.