Like Delta Air Lines with its own refinery purchased to smooth out fuel costs, and even more like General Motors and Ford Motor with similar joint-ventures with start-up companies, Audi AG has teamed up with a couple of new energy companies to develop clean, sustainable fuels. The most immediate plan is with Stuttgart-based SolarFuel, which is constructing a plant to produce “e-gas” natural gas to fuel cars like the TCNG version of the Audi A3 Sportback it unveiled at the Paris auto show. The A3 TCNG, which has both a 13.2-gallon natural gas tank and a 13.2-gallon petroleum gas tank, and a range of 775 miles, goes on sale in Germany May 2013,the same time the automaker expects the clean, synthetic natural gas to be ready. Ultimately, it comes down to the problem afflicting the auto industry since the U.S. began imposing fuel economy standards in the 1970s. The standards don’t really affect oil companies. Sure, they long ago hadto get the lead out, and more recently in the U.S. had to severely reduce diesel fuel sulfur levels to closely match the level in the European Union, but there’s no regulatory impetus for Big Oil to invest in alternatives the way automakers need to invest in alternative fuel powertrains. Audi engineers say oil companies simply don’t want to invest in alternatives so long as fossil fuels remain relatively cheap. Their goal for both the e-gas in Europe and thebiofuels in North America are to make these fuels cost effective for the consumer and for themselves by assuming an oil price of $100 perbarrel. The two tanks fit behind the twist-beam rear suspension of Volkswagen Group’s new MQB architecture (VW Golf, and next-generation Passat, plus future compact and midsize crossovers) and are made of carbon-fiber-reinforced plastic. The A3’s 1.4-liter turbo four has separate injection nozzles for natural gas and for petroleum gas, and Audi says the car can switch between the two seamlessly for the driver. SolarFuel’s plant will convert hydrogen to synthetic natural gas through a process called “methanization,” creating a carbon dioxide-neutral fuel it can feed backinto the grid. Both the dual-fuel version of the A3 and the synthetic natural gas will be available only in Germany, which already has 1000 natural gas outlets for passenger cars, compared with just 300 in all of the United States. Audi AG’s other alt-fuel joint venture is with Bedford, Massachusetts-based Joule, which is constructing a plant in Hobbs, New Mexico, with Audi that will produce synthetic ethanol and diesel biofuels. Joule makes these biofuelsby combining living bacteria with CO2 and brackish-, salt-, or wastewater. The synthetic ethanol is skimmed from the top, though Audi says the process to do the same for synthetic bio-diesel still needs work. Joule’s diesel biofuel also would still require aftertreatment to meet U.S. emissions standards. Audi’s plans for the joint venture with Joule are less defined than its plans with SolarFuel. After Joule finishes its New Mexican plant next year, the automaker hopes to get the biofuels on the North American market and begin testing it in its own fleet. *. Audi A6 TDI/hybrid: A 48-volt electrical machine replaces the pinion starter, and a DC-to-DC converter converts it to 12 volts. As with the A1 plug-in’s gas engine, the A6’s 3.0-liter diesel V-6accelerates the big sedan to 30 km/h (about 19 mph). The clutch allows freewheeling mode. Start/stop works under 15 km/h (9 mph) and a modified belt system keeps the air conditioning or heating running while the engine is shut off. Transitions on my short drive were seamless, you need to check the gauges to figure out which mode you’re in, and the performance is reasonably good for the big sedan. *. Electric turbocharger: It’s not a green technology , per se, but an outgrowth of the TDI hybrid’s DC-to-DC converter. A 48-volt electrically powered turbocharger also uses the converter system to work with the car’s standard 12-volt system for very low-end power boost. A conventional exhaust turbo kicks in higher up the rev range. Audi presented thissystem in an A7 TDI V-6 and an A6 gas V-6. I drove the A7 TDI. The dual-turbo engine is rated 308horsepower and 480 pound-feet with the diesel. Audi demonstrated back-to-back runs with a switch that turns on or off the electric turbo, and the difference is dramatic. With only theexhaust turbo, the A7 had that typical diesel bog-down step-off. With the electric turbo switched on, power was immediate, like say a twin-turbo gas V-12. Even as automakers switch to alt-fuels and alt-powertrains for the masses, it’s clear there still will be big, quick, powerful sedans for those with means.