Surprise! It's the diesel R8

We knew Audi was planning something big in Detroit, and here is it: the world's first diesel supercar.

This is the Audi R8 V12 TDi, and although it's being billed as a concept, it should be on the road within a couple of years.

Tearing massive holes in the road, quite possibly. The R8 V12 isn't a cooled-down version of Top Gear's Car of Year: in fact, the diesel version is billed as faster, more powerful and - of course - far more torquey than its petrol brother.

A few raw figures for you. The R8 TDi gets a 5.9-litre V12 twin-turbo diesel with 493bhp and, more scarily, a massive 738lb ft of torque. That'll shove the R8 to 62mph in 4.2 seconds - nearly a half-second quicker than the petrol version - and on to a top speed 'well over 186mph', according to Audi.

Awesome performance, in other words. But it won't come at the expense of economy: The R8 V12 returns 23mpg - just 4mpg less than the V6 TT - and although there's no word on emissions, Audi says it'll meet the 2014 Euro 6 regulations.

All of which sounds like an intoxicating combination, leaving us with just one worry: weight. Audi doesn't quote how much heavier the TDi unit is than the petrol V8, but too much extra weight could play havoc with the R8's delicate, wieldy handling.

However, Audi has managed to shave some weight from the diesel block by using stronger cast iron, allowing for thinner crankcase walls, which reduces weight by some 15 per cent.

Although the bodyshell of the R8 V12 is taken straight from the petrol version, the diesel-burner does get a few cosmetic enhancements. There's a glass roof with a NACA air duct in the middle, as well a new single-piece front bumper and bigger air intakes.

Inside the cabin, there's a bit of extra carbon fibre and, you'll notice, a manual gearbox. Word is that all the diesel torque would simply devour the DSG ?box, so a six-speed shifter it is - good news, because that's the ?box we liked on the petrol R8 anyhow.

We won't see the diesel R8 on the road until after the new Lamborghini Gallardo - and you'll see a V10 petrol version of the R8 beforehand, too. The V12 TDi could be the most tempting of the bunch, though - if the Audi engineers can make it handle like the petrol version. Here's hoping.

2009 Hyundai Genesis

It's the start of something, all right. The Genesis sedan marks the debut of Hyundai's first-ever V-8 engine, its first-ever rear-wheel-drive platform, and its first foray into the luxury car arena. Hyundai is positioning the car as a BMW 5-series/Infinti M/Lexus GS competitor, priced to match the rear-wheel-drive domestic-brand competition (Chrysler 300/Pontiac G8).

If you doubt Hyundai's luxury intentions, check out the car's list of available equipment, which includes intelligent cruise control; adaptive headlights; heated and cooled seats; a rearview camera; high-end audio (by Lexicon) with NavTraffic, iPod and USB inputs; Bluetooth; keyless ignition; leather seating and even a leather-wrapped dashboard.

Like its competition, the Genesis will offer 6-cylinder or V-8 power. Two V-6 engines are rated at 268 hp and 290 hp, while the all-new V-8 generates 368 hp (on regular fuel) and 375 hp (with premium) from its 4.6 liters. All engines are teamed with a 6-speed automatic transmission and drive the rear wheels. (No all-wheel-drive option will be offered.) Hyundai claims the 8-cylinder version will reach 60 mph in less than 6 seconds.

The Genesis goes on sale this summer. The car will come in a single trim level. Prices for the base V-6 engine version will start under $30,000 (though probably not far under), while the V-8 should be around $35,000.

This chassis will also underpin a production version of the Coupe concept seen at the 2007 L.A. auto show, which likely will reach showrooms toward the end of the year.

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2009 BMW 335d and X5 xDrive 35d

BMW is preparing to put the 'd' back into the United States market. Starting in the fall of 2008, two models will be available with a 3.0-liter biturbo in-line six diesel engine. They'll make their first appearance at the 2008 North American International Auto Show.

The 335d and X5 xDrive 35d will be the first BMW diesels sold in the U.S. in well over two decades. The Advanced Diesel with BluePerformance is a version of BMW's diesel in-line six that's already sold in Europe, where diesels account for two-thirds of the company's new vehicle sales. The addition of BluePerformance urea injection allows these models to be sold in all fifty states, even those following California's strict emissions standards.

BluePerformance uses a solution called AdBlue, which is basically urea (yes, that urea) that is injected into the exhaust gas to turn nitrous oxides into nitrogen gas and water vapor. This works with a diesel particulate filter to reduce emissions. The AdBlue solution should only need to be replenished during regular service intervals, and BMW will include free refills in its 4-year/50,000-mile maintenance program. This is the same system that Mercedes-Benz uses in its Bluetec diesels.

But you don't care about any of that, as long as it means you can get a 3-series with 265 hp and - get ready for this - 425 lb-ft of torque.

Wait, 425 lb-ft? As in 130 more than the new M3? Yes, indeed. What's more, two differently sized turbochargers help make that torque available at only 1750 rpm. The smaller of the two spins up first to minimize lag at lower rpm, and the larger turbo comes on at higher engine speeds to keep things going.

The diesel-equipped 3-series has a claimed 0-to-62-mph time of 6.2 seconds - a claim we'd believe, since several Automobile Magazine editors have driven the car in Europe. The 335d is estimated to return fuel economy of 23 mpg in the city and 33 mpg on the highway. The X5 xDrive 35d will take an extra second to reach 62 mph and will consume diesel at a rate of 19 mpg around town and 25 mpg in highway driving.

If these models take hold - and we sincerely hope they do - we expect to see this engine in additional U.S. models. And there's more where that came from, because BMW has a diesel V-8 and three four-cylinders in various models running around the Continent.