TDI's Time To Fly

Europe's largest-volume seller of turbodiesel engines for light vehicles, Volkswagen AG, unleashes to its U.S. arm two new diesel models to magnify the auto maker's exposure of diesel power to North American customers.

With U.S. gas prices continuing to spike in excess of $2 per gallon, VW couldn't have picked a better time to expound the gospel of new-age diesel.

Its two new cutting-edge TDI (turbo direct injection) diesels — the Passat and Touareg — are polar opposites in performance and price, but both are formidable efforts that will force gasoline-powered competitors to take notice. Note to those who think the biggest, baddest SUV available to civilians is General Motors Corp.'s Hummer H2: You're so five minutes ago.

The new Touareg TDI packs a 5L V-10 variant of the TDI with 310 hp and a Warsaw Pact-violating 553 lb.-ft (750 Nm) of torque. The V-10's mighty torque twist leaves the Hummer 6L gasoline V-8, at 325 hp and 365 lb.-ft. (495 Nm), looking wimpy, in addition to surpassing the performance of its gas-guzzling V-8 counterpart.

We are no fans, however, of the Touareg's unconscionable curb weights. The TDI model tops all versions at a scandalous 5,825 lbs. (2,642 kg). So it's testimony to the V-10 turbodiesel's magnificent grunt that even through the standard 6-speed automatic, it can launch the Touareg TDI to 60 mph (97 km/h) in 7.5 seconds. The gasoline V-8 Touareg does the same run in 7.6 seconds.

Then there is the fuel economy, diesel's traditional trump card: 17 mpg (13.8L/100 km) city and 23 mpg (9.2L/100 km) highway. That's practically physics-denying for a 3-ton SUV.

Once you get over the superficial disappointment of the SOHC/2-valve-per-cylinder setup, VW's TDI V-10 is a tech-geek delight: all-aluminum construction with cylinder walls plasma-coated to reduce wear; twin turbochargers with electrically adjusted vanes; intercooling not only of the intake charge but also the recirculated exhaust gas and an exquisite gear drive for the valvetrain and ancillaries that eliminates drive belts.

And of course, the direct fuel-injection system uses VW's exclusive combination fuel pump/injector for each cylinder to generate the spectacular 29,700-psi (2,050-bar) injection pressure that quiets the diesel chatter and maximizes power and fuel economy.

The stunning V-10 and all the other Touareg niceties that come with the TDI package — it's the Touareg-family flagship — are dear. A $57,800 base price surpasses $60,000 by adding a few alluring options that probably should be standard. Volkswagen says the 500 earmarked for the U.S. should find homes (though we saw a few being peddled by dealers on eBay).

At the other end of the scale is the new Passat TDI. With fewer than half the Touareg TDI's cylinders, the Passat gets along quite nicely, thanks, with a 2L 4-cyl. turbodiesel that produces a less-bombastic 134 hp and 247 lb.-ft. (335 Nm) of torque. As with the Touareg, the only available transmission is a sequentially shiftable Tiptronic automatic; the Passat's enjoying five forward speeds rather than six.

The Passat TDI's forte is in-gear acceleration: Stomp it at 70 mph (113 km/h) and it hauls itself to 90 mph (145 km/h) with verve — serious enough to drop a lot of 6-cyl. midsizers like a bad habit. Once under way, one forgets the unhurried 10.2 seconds it takes the Passat TDI to gather itself up for the 0-60 mph jaunt.

The official fuel-economy figures are 27 mpg (8.7L/100 km) city and 38 mpg (5.7L/100) highway. Fuel-sipping like that isn't assimilated until you realize you can't remember whether you bought fuel last week — or was it the week before?

There are two body styles for TDI-carrying Passats, sedan and wagon, and the price starts at $23,060 and $24,060, respectively — $205 more than their 4-cyl. gasoline counterparts.