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In the century or so of the automotive era many icons have come and gone, but several live on with us today. Cars like the Ford Mustang, Porsche 911, and Chevy Corvette all fitting the bill. Most companies from the old guard have at least one in their stable, but how unfair is it for an automaker to have three? Especially when they are all versions of the same car.

After more than 25 million sales spread over six generations, the Volkswagen Golf needs no introduction. But neither do two of its variants: the diesel-powered TDI and the ultra sporty GTI – the Golf name omitted from the latter in the U.S. because many autocrossers are apparently also label queens (but I still wish that I could drive as well as they can, so please don’t run me off the road for pointing that out.)

At first blush these two compacts appear to be polar opposites on par with, well, the Earth’s poles. One is a high-mileage penny pincher, the other a high-strung extrovert. But look deeper into the specs and you’ll find that they share quite a bit.

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The cars have the same basic three or five-door hatchback body and, aside from a few pieces of trim, identical interiors. Both come mostly loaded, save for optional Bluetooth, sunroofs, navigation systems - which can’t be had on run-of-the-mill Golfs, and leather seats unique to the GTI. The cabin isn’t particularly stylish, but it is impeccably finished, if you can overlook the flimsy climate control knobs. With chrome trim, soft-touch plastics, and a few spools of red stitching in the GTI, you wouldn't think twice if it were covered in Audi logos.

The pair are also fitted with like-sized tires, although the wheels on the TDI are actually wider than the ones on the GTI - a fact that makes my head hurt. Six-speed manual transmissions are standard, with VW’s quick-shifting six-speed automatic Direct Shift Gearbox (DSG) a $1,100 option.

Open either hood and you’ll find a 2.0-liter turbocharged four-cylinder engine between the front wheels, but that’s where the similarities end. The motor in the TDI is one of today’s much ballyhooed clean diesels, and a favorite of the green set thanks to a 42 mpg highway rating. With just 140 hp on tap it won’t win you many awards at Bonneville Speed Week, but 236 lb-ft of torque gives it plenty of punch for passing - good for when you’re stuck behind a semi on I-80 in Wendover. Nearly silent on the move, with a loping gate, the TDI is the premier compact of the moment for highway cruising, bar none.

Throw a couple of turns into the mix and you’ll discover that the TDI can also hold it’s own in the handling department. It has a sport-tuned suspension that’s not available on standard Golfs, and rabbit-quick steering response that is always one step ahead you. It’s well-balanced through curves and ready to bring the rear end around with a commanding lift of the throttle, or tap on the brakes. Combined with arrow-straight tracking on the highway, after a few dozen miles you can’t help but think, “it doesn’t get any better than this.”

But it does. VW measures the quickness of the DSG’s gear changes in milliseconds, and that unit of time would be appropriate to describe how long it took me to forget about the TDI and fall in love all over again when I eased into the GTI.

The flat-bottomed sport steering wheel and ball-topped gear selector set the mood, but the exhaust note alone is nearly enough to justify the price premium that the $23,664 GTI commands over the $22,354 TDI, its bellowing sound far out of character for a four-banger.

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VW held the line on power for 2010, sticking with the 200 hp and 207 lb-ft of torque of last year’s model, but it’s so useable and spread so linearly across the rev range that you can live without the peaky delivery more pressure from the turbo would likely create. As it stands there’s no turbo lag, and even half-throttle acceleration returns a nice puff from the pipes with each upshift. Floor it, and the pop is more like what comes out of an air cannon...one the size of the big gun on a battleship. VW/Audi uses this engine in a number of vehicles, but it is such a perfect fit for the GTI, it might as well be a glass slipper.

Set a notch lower than the TDI, the suspension in the GTI is noticeably firmer, but the ride is far from harsh. Even if it was, the handling is so much sharper that the tradeoff would be worth it. The car has the same neutral feel of its chassis mate, and power understeer is kept in check by an electronic differential that can send extra torque to the outside front wheel when needed.

The only real letdown on the performance front is a surprisingly soft brake pedal - at least on my test car. This may have been the result of it having suffered through 4000 miles of lead-footed journalism, but the one in the fresher TDI wasn’t much better.

Rated at 32 mpg highway, the GTI is second only to the MINI John Cooper Works in the over-200 hp club, but makes up for it with a much shorter name. That kind of efficiency may not do the TDI any favors in the sales race, but the diesel holds its own trump card in the form of a $1,700 alternative fuel tax credit from the feds.

Could you go wrong with either of these cars? Time will tell...or maybe it already has.

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2010 Volkswagen Golf TDI / GTI

Base Price: $22,354/$23,664

As Tested: $28,190/$28,684

Type: 5-passenger, front-wheel-drive, 3 or 5-door hatchback

Engine: 2.0L turbocharged 4-cylinder diesel/2.0L turbocharged 4-cylinder

Power: 140 hp, 236 lb-ft torque/200 hp, 207 lb-ft torque

Transmission: 6-speed automatic

MPG: 30 city,42 hwy/24 city, 32 hwy

What do you think of the TDI/GTI?

Send your comments to foxcarreport@foxnews.com