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In another "near-production" study (read: soon-to-be-released) from VW/Audi, the firm makes an economical splash at the Paris Auto Show with its A4 TDI concept e. Using an efficiency-tuned version of the 2.0-liter diesel engine found in the Volkswagen Jetta TDI clean diesel that's been wowing enthusiasts and setting mileage records, the A4 makes due with 20 less horsepower (120 total) and about 22 less lb-ft. torque (214) - plus a few other econo-tricks - in the name of astonishing efficiency from an approximately 3,500-lb. sports/luxury car. How does 58 mpg sound to you and your wallet?

The econo-tricks mentioned above are similar to those employed on hybrids and fuel-efficiency models popping up across the automotive spectrum, and include items like the low-rolling resistance tires found on cars like the Chevy Cobalt XFE, regenerative braking employed by the likes of the Toyota Camry Hybrid, the increasingly popular engine stop/start feature making its way into luxury brands like the BMW 3-series, and electrically-boosted power steering like that found on products like the new Acura TL. In addition to these more predictable fuel-saving measures, the A4 goes the distance with soft springs on the intake valves (creating less drag on one camshaft, ergo less fuel-sipping drag on the engine), and variable-rate technology on its fuel pump and A/C compressor that uses only as much engine energy as needed for those items, not one iota more.

Taking efficiency to the extreme are electrically-actuated rear brakes, magnesium parts in the six-speed transission with its economy-minded ratios, and even an insulating wrap on the transmission to heat its fluid more quickly, all this in the name of reducing friction and therefore the energy costs of moving this slick new A4 down the road.

Even the vehicle's electronics get in on the fuel-saving game, with the navigation system choosing the most efficient route possible, or the car's electronics running the driver through an "economy training program." Cars may soon be forcing us to get involved with driving...it's nice to think that we may be challenged behind the wheel once more, what with distronic cruise control, lane-departure warnings, and stability control taking the helm these days while many drivers are too busy texting to be bothered.

Of course, there is a performance price for high economy. 10.7 seconds to 60 mph hardly rates as exciting, though it is on par with the Toyota Prius. And with stellar mileage, suave styling, and tenacious handling courtesy of Audi's stiff new A4 platform wearing 225/50 low-rolling-resistance tires, the A4 should put the appliance-like Prius to shame. Suddenly the thought of driving an economy car doesn't seem so depressing.

Plenty of low-end torque from the little turbodiesel should make stoplight-to-stoplight easy and stress-free (much like the insta-torque of an electric motor from rest), and as long as you plan ahead for freeway on-ramps, a range of 996 miles (assuming the standard 16.9-gallon fuel tank) should provide more than adequate compensation for reduced 0-60 mph times.

Wonder what mileage-busting Australian couple John and Helen Taylor could net with an A4 TDI concept e...--Colin Mathews

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What to do when you are a dinosaur among a herd of gazelles? Brag that you are the sprightliest dino out there, even though the gazelles may be laughing hysterically and running circles around you. Dino: "But I can carry seven people! And tow things!" Crossover Gazelle: "Uh, yeah. So can I. And I can go a lot further between watering holes and feedings." Lonely times, indeed, for the full-frame, V-8-powered SUV. If sales fall any further, they might make the National Wildlife Federation's endangered species list.

The 2009 Lincoln Navigator 4X2 now earns...drumroll...14 mpg city and 20 mpg highway. Respectable for the class, but significantly lower than both the Chevrolet Tahoe and Dodge Durango two-mode hybrids. Not to mention diesels like the Mercedes GL 320 BlueTEC (EPA 17/23 mpg). Clearly, Ford is trying to find a silver lining in its current situation, employing new transmissions and massaging existing engines while holding its breath for true engine breakthroughs still in the works.

Claiming the fractional improvements in mileage are due to "architectural changes and systems engineering enhancements," this latest announcement seems to be spawned primarily by "using aggressive deceleration fuel shut-off." Whenever you fully release the accelerator pedal in a modern car, the fuel injectors shut off to consume gasoline. But injector shutdown and startup must be done carefully to avoid being noticed by the driver as well as to avoid increased tailpipe emissions. Ford has increased the speed of this process, resulting in quicker injector shutoff and therefore less fuel used while coasting and braking. Cool, but a far cry from regenerative braking.

While it's great that Ford powertrain engineers are working on fuel economy subtleties such as these, we won't be truly excited until we see technologies that significantly increase fuel economy such as its upcoming EcoBoost engines (set to debut in the 2009 Lincoln MKS) and its upcoming medium-size turbodiesel V-8 for light trucks and SUVs.--Colin Mathews

Bentley's storied past has been filled with exclusivity, and the firm figures that the ending of the Arnage line in its current iteration (extant some 10 years) deserves fanfare of the extra-exclusive variety. It is in this spirit that Bentley announces the aptly named Arnage Final Series, to be produced in a run of only 150 vehicles. In yet another exclusive, the announcement itself marks the first time Bentley has made mention that production of a current-generation Arnage is ending.

The Arnage Final Series marks the 50th anniversary of the company’s "iconic V-8 engine," a deliciously big motor still displacing a behemoth 6.75 "litres," but now replete with 500 horsepower due to the same twin turbochargers found in the Arnage T. Through its balanced, blueprinted life, this engine has motivated plenty of Q-ships out of Crewe with swiftness and serenity. Speaking of exclusivity, for years, Bentley wouldn't even divulge its exact displacement.

Apart from "Final Series" badging on the front wings, Bentley-philes will be able to tell the Arnage Final Series by outward cues like a retractable flying-B bonnet mascot, a Bentley "jewel" fuel filler cap, twin exhaust pipes, and body-colored headlamp bezels. Moving to the cabin, both front doors are paved with "Final Series" treadplates, both brake and accelerator are of drilled alloy, "waistrails" with an inset chrome strip and recessed Bentley marque badges make a first appearance ever on the Arnage, and, the coup de grace, you will be able to enjoy your Patron Silver from none other than "Final Series" stainless steel flask and shot glasses (and if you have any idea what a “waistrail” is, then you are a bigger Bentley-phile than I).--Colin Mathews

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Performance sedan fans around the world, rejoice. In March 2009, you should be able to get your hands on the new Audi S4/S4 Avant, which Audi promises will accelerate to 62 mph in 5.1 seconds and manage an average U.S. EPA rating of 24 mpg.

In a surprise move, Audi, one of the automakers responsible for breathing new life into the turbocharged engine in the last decade, has turned to supercharging for remarkable power and efficiency gains in its new uber-performance sedan and wagon based on the new A4 platform. The new mill cranks out 333 horsepower at and about 325 pound-feet of torque in a flat plane from 2,500 to 4,850 rpm. Of note, this also marks a departure for Audi high-performance and S-line engines, which tend to make considerably more horsepower than they do torque (R8: 420 hp, 317 pound-feet).

The new supercharged, 3.0-liter TFSI V-6 makes do with two fewer cylinders than the previous S4, and Audi acknowledges that the "T" in the engine nomenclature no longer denotes turbocharging but rather "the concept of supercharging in general." Much like the new Chevrolet Corvette ZR1, the supercharger design is of a twin-rotor, four-vane design, and we wonder if Audi also benefited from notable efficiency gains in supercharging recently developed by the Eaton company and employed on the ZR1 and CTS-V. The cooling effect of direct injection simplifies intercooling and enables the supercharger to be located directly behind the throttle valve, also increasing efficiency of the package.

Also big news is the rollout of Audi's new seven-speed DSG gearbox, known in this application as S-Tronic. The S-Tronic is optional, and with yet another ratio to choose from compared with the excellent six-speed unit fitted to some of its products, performance is likely to be quite breathtaking. Audi claims that the the S4 will accelerate from 0-60 mph in about 5 seconds and from 50-75 mph in about 4.4 seconds--fleet performance indeed. Standard is a traditional six-speed automatic with a torque converter. Paired with either transmission, standard, is Audi's quattro permanent all-wheel-drive system that is biased 60 percent to the rear in normal conditions.

Taking a page from Acura's SH-AWD playbook--then making a few addendums of its own--Audi introduces its active sport differential, an option with Audi's Drive Select, also itself an option on S4/S4 Avant. Like SH-AWD, active sport differential spins the outside rear wheel with greater urgency through turns. Unlike SH-AWD, Audi's system is active and effective even when the car is coasting or in between throttle applications.

As in some other Audi products, Drive Select is an option. The technology, which adjusts shift points on the seven-speed S-Tronic transmission, changes throttle characteristics, and affects steering effort, must be ordered with at least one of the following three options: the active sport differential, adaptive shock absorber control, and dynamic (active) steering.

Changes that further differentiate the S4/S4 Avant from its A4 foundations include special aprons, aluminum-look exterior mirrors, 18-inch S-design wheels, side rocker panels, a rear spoiler, and quad exhaust outlets. Inside, gray dials with white needles let you know you're behind the wheel of a special A4, and sport seats feature electric lumbar supports with pull-out thigh supports. The standard interior color is black with brushed-aluminum highlights, though carbon, birch, or stainless steel highlights are available.

Should the killer power, sybaritic interior, or sublime handling fail to remind you you're in a very special A4, the S4 badges in places like the seats, steering wheel, and key will remind you of your capability to blow the doors off the already athletic A4 sedan.

We'll have more for you from the 2008 Paris Auto Show next week, when the S4 makes its world debut. The S4 goes on sale in America next fall for a price similar to today's S4.--Colin Mathews

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With the advent of its new S400 Hybrid, Mercedes-Benz says it has the greenest internal-combustion-powered luxury sedan on the planet.

It may sound like a mouthful, but each part of that description points to an S-Class with impressive fuel economy rating of nearly 30 mpg in the European cycle--making it nearly as economical as some of Benz's European diesel offerings, while keeping the trappings of the range-topping S-Class intact. The S400 Hybrid also accelerates to 60 mph in about 7 seconds, preserving the performance expected from a Mercedes sedan.

Mercedes gets those lofty fuel economy figures with what it says will be the first lithium-ion hybrid batteries to hit the road. That's in a series-production vehicle, which means by Benz's accounting, the hand-built Tesla Roadster doesn't count. With its 2009 model-year designation in Europe, the S400 Hybrid will beat the 2011 Chevrolet Volt and the coming Toyota Prius plug-in hybrid to market by at least a calendar year.

The S400 Hybrid is based on the existing S350 sedan; its batteries and motors are teamed with a 3.5-liter gasoline-powered engine with 279 horsepower. The electrics add another 20 hp and 118 pound-feet of torque at zero rpm. The standard seven-speed automatic has been modified for hybrid operation, and stop/start functionality is hardwired in the new hybrid's electronics. Energy is captured for battery charging through regenerative braking.

Mercedes will sell the new hybrid in the United States starting a year from now. No pricing has been announced. We'll have more on the Hybrid, and on the Mercedes concept Fascination, from the Paris auto show in two weeks' time.

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