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BMW's 7-Series ActiveHybrid Concept is on display this week at the Paris auto show.

The ActiveHybrid relies on a 20-horsepower, 155 pound-foot electric motor integrated with an automatic transmission to enable fuel efficiency gains of up to 15 percent over a new nonhybrid 750i. Motivated primarily by the 5.0-liter direct injection twin-turbo V-8 seen in the new 750i and current X6, the electric motor eliminates the the starter motor and alternator, increases the efficiency of the stop/start function seen on an increasing number of BMWs, and uses regenerative braking to more than recoup the parasitic power losses from items like air conditioning and infotainment systems.

Eliminating the alternator, especially in a luxury vehicle like the 7 Series, makes a significant contribution to energy savings. The more comfort/convenience items used in a vehicle, the more drag a traditional alternator places on the engine, consuming more gasoline in the process. By placing these electrical loads solely on the vehicle's battery, which is now recharged during coasting and braking, as well as driving the air conditioning compressor electrically instead of off the crankshaft, significant gains in fuel economy are realized. Energy that used to literally go up in the air as heat during braking is now recaptured and used to power many items in the vehicle.

BMW was a participant in the group that worked on incorporating electric motors into a vehicle's transmission for hybrid operation. GM, Chrysler, and Mercedes also participated, and some products (such as the Chevy Tahoe Hybrid and Dodge Durango Hybrid) are already on the road. Mercedes' forthcoming S400 Hybrid appears to use the same transmission-mounted electric motor approach.

Energy saving technologies such as these found on the 7 Series ActiveHybrid Concept will be necessary if luxury carmakers expect to continue selling powerful gasoline vehicles in significant numbers in the United States. The U.S. market, having enjoyed some of the cheapest gasoline in the world, has become the largest market for big-engined gasoline luxury vehicles, and automakers face engine downsizing, diesels, or fuel-saving technologies like gas/electric hybrids if their products are to remain competitive.--Colin Mathews

Believing that buyers of compact cars shouldn't have to deal with economy-sounding radios and the lack of affordbale nav and in-car communication systems, automaker giant Nissan is rolling out its new Connect System. Described as an "integrated audio, navigation and communication system," the system promises high-fidelity audio, Bluetooth integration for mobile phones, and even wireless playing of bluetooth-equipped phone/mp3 players including track listings and playback control through the Connect central 5-inch touch screen interface. An auxiliary jack is also incorporated for playback of non-Bluetooth music devices.

The navigation system can communicate with users in nine languages total, and the navigation features a an Eco mode that calculates a route based first and foremost on increasing fuel economy. A USB input is integrated into the unit, and is mounted in the storage are on top of the dashboard alongside the auxiliary jack, allowing MP3 players, hard drives, or other music players to be stored securely out of sight while remaining connected to the system. Nissan's Connect system was developed in conjunction with the car multimedia division of the Bosch Group.

This is the kind of smart thinking we like from automakers, and it can only help to increase the appeal of small cars to buyers who are accustomed to their rolling office/gymnasium/movie theater monster trucks, Luxury SUVs, and 4,000-lb.-plus crossovers. American buyers in the Heartland associate economy cars with horrible things like manual crank windows, tinny two-speaker radios, no A/C, and God-forbid, having to read a map or ask for directions at the gas station. The launch of Nissan's Connect is well-timed with a market and a public that is downsizing, and now fans of tech-laden luxury SUVs can more easily step down into miserly modes of transportation without feeling they've been downgraded.

Nissan Connect will make its debut on the new European Note vehicle, to be sold beginning in 2009. Another vehicle offering navigation at a low price-point is the '09 Suzuki SX4, where an integrated Garmin navigation unit comes standard on the Sport model starting under $16,000. However, the Suzuki doesn't promise the Connect's bluetooth capabilities nor entertainment/mp3 connections.--Colin Mathews

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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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General Motors' ubiquitous 3.8-liter V-6 is soon to become extinct. For '09, it is replaced by GM's (more) modern 3.9-liter V-6 in the Buick Lucerne, leaving it barely hanging on in the Buick LaCrosse and Pontiac Grand Prix, which share a platform. Some will cheer the eventual passing of this antediluvian push-rod motor, while others will wax poetic about its bulletproof reputation, easy low-end torque, and storied supercharged and turbocharged versions.

Neither LaCrosse nor Grand Prix are competitive players in the crowded mid-size sedan/sport sedan segment (think Honda Accord, Toyota Camry, Chevrolet Malibu...but of course Buick would like you to think Lexus ES350, and Pontiac would like you to think Acura TL). That's partially due to their base engine, the 3.8-liter V-6, which is coarse and inefficient compared to its rivals' modern powerplants.

The 3.8-liter is of the ancient, but space-efficient, push-rod, overhead valve design that Chevrolet popularized with its small-block V-8 of the 1950s. In fact, the first version was a shortcut engine originally engineered by Buick in the 1960s simply by lopping two of the cylinders off its short-lived 3.5-liter V-8, though a cast-iron block replaced the V-8's aluminum block for cost reasons. According to Wikipedia, Buick launched it as the "Fireball V-6" in 1962.

In later iterations, the engine grew to its current 3.8 liters, sharing identical bore spacing and V-angle (90 degrees) as a larger Buick V-8 produced in the same plant.

Alas, a 90-degree V-6 isn't a very happy, smooth-running beast unless balance shafts quell vibrations in the compromised design (a 60-degree V-6 sends balanced power pulses to the crankshaft). The 3.8-liter loped along under the hoods of countless GM cars without balance shafts until the 1980s, at which point it became a much more pleasant and smooth-running motor.

The 3.8-liter V-6 was always meant as a low-rpm torque producer, and was employed in posh, floaty vehicles like Buicks, Oldsmobiles, and upscale Pontiacs where an understressed motor was meant to connote luxury. But being of old-school design, it didn't like to rev, and so it was perfectly happy torquing around town under grandma's gentle right foot. It got a serious boost via turbocharging in the awesome Buick Regal GNX of the '80s, which could easily smoke muscle cars like Mustangs and Corvettes of the day. But usually it was under the hood of your mom's '98 Regency Brougham or your dad's Bonnneville SE. Or in miserable economy, emissions-choked sleds like the 1977 Buick version that huffed out all of 110 hp.

GM's serious R&D has more than kept push-rod valve actuation a competitive technology (7.0-liter, 505 horsepower Z06 V-8, anyone?), and some of those advancements have trickled down to the venerable 3.8-liter. It is now relatively civil, smooth, and torquey. But it's still not happy at high rpm, and it can't compete with GM's own 60-degree push-rod V-6 family in both 3.5- and 3.9-liter flavors. That 3.9-liter benefits from variable valve timing, making it both more efficient, more powerful, and smoother due to its balanced nature than the 3.8, hence GM's decision to put it in the Buick Lucerne as base engine for '09.

Once GM kills the Grand Prix (the Pontiac G8 slots into that niche now), and updates the LaCrosse, we expect this engine's fate to be sealed. The engine won't go out without leaving a mark; Wikipedia calls it "one of the most-produced engines in history," with more than 25 million having rolled off the assembly line.--Colin Mathews

Last Friday night, on my way to fill up at Refuel Biodiesel in Atlanta, I noticed a bizarre sight: a line of frustrated drivers, some with hazards flashing, some even clogging Cheshire Bridge Road, all stranded and waiting for the precious few operable pumps at the neighboring Chevron and Citgo stations. I stared in amazement, snapped a few phone pics, and drove a few miles to the biodiesel station where I filled up, waiting only for the pump to click off after filling my tank with a blend of mildly altered vegetable oil and Ultra Low Sulfur Diesel Fuel.

I purchased a 1982 Mercedes-Benz 300TD Turbo Diesel (TD is Mercedes-speak for "diesel wagon") from a client in Los Angeles back in 2006 for $500 ("you want that piece of junk!?"). A plastic surgeon in toney Hancock Park, my client had once used the car with a hired driver, no less, to shuttle his kids around in the '80s and '90s. The driver and a shady mechanic in L.A., respectively, drove the car into the ground and did questionable repair work on the workhorse Benz. And then it sat neglected in a Los Angeles driveway for years with 300,000 miles on the clock, flat tires at all four corners, and a growing network of cobwebs inside and out.

The potential of freeing myself from foreign oil, rising energy costs, and just the sheer challenge of getting the old lump driving again were too much to resist. The project began, and I threw $500 at the wind, knowing I'd have fun whether it ever ran or not.

A cross-country trip and a couple of years later, the Benz is running splendidly, now with almost 330,000 on the odometer. It doesn't look so splendid, with a dying cheapo paint job and a couple of body panels from the junkyard. And apart from my own satisfaction and cleaner emissions out the tailpipe, my use of biodiesel has never really benefited anything but my ego and my obsession with mechanical wonders. In fact, I've spent thousands fixing, wrenching on, and perfecting the car.

But last Friday night, the benefits of driving an alternatively fueled vehicle came vividly alive. It was remarkable not to be tied to petroleum for my transportation, and I marveled that as some Atlantans were grounded or waiting in line, I was driving on a full tank through silent streets.

My mobile mechanic friend Dan Halfhill, in Malibu, Calif., who got me into this diesel Benz obsession, has been urging me to take this all a step further. The easygoing, mechanical genius owner of Rollin' Wrench told me on a recent trip to L.A., "Come on, man. You need to go veggie." He started with biodiesel--which is just vegetable oil that has been chemically altered to a lower viscosity very similar to diesel No. 2--back in '05 or '06. He initially warned against using unaltered vegetable oil as its thickness can clog fuel systems and harm injectors. But now Dan and others have engineered systems that filter the veggie oil, heat it to the proper viscosity, and then inject it right into the engine.

If this surprises you, know that Rudolf Diesel won the Grand Prix at the 1900 World's Fair, Paris, where his "heat engine" ran solely on peanut oil. They didn't have diesel No. 2 back then.

Before advancements in heating and filtration, I was wary of potentially destroying my engine, and so I've stayed with biodiesel, which poses zero risks. But it does cost roughly the same as diesel, so again, I'm not saving any money. I'm just doing something green, and spewing out remarkably clean tailpipe emissions in the process. But Dan has now converted countless Benz diesels, and even his own Ford Econoline diesel work van, to run on pure waste vegetable oil (WVO). With tens of thousands of miles backed by an experienced mechanic's confidence, I believe I'm finally ready to make the switch to waste vegetable oil.

Having restored many of the old Benzes he's converted to run on vegetable oil, Dan has some serious connections in the automotive painting and detail business. The thought of a respectable, affordable paint job is very tempting. That and a set of slick 16-inch Mercedes rims with new tires Dan has all but promised to give me if I just take the plunge and go pure veggie...

That's it! It's time to go back to California. This time, powered by nothing but waste vegetable oil for all 2,257 miles. It looks like early December is going to be the best time for the trek. And perhaps when I return to Atlanta, my ride will finally look as good as it drives.

Now to start ordering parts and pieces.--Colin Mathews