It's going to take Audi a long time to live down its U.S. chief's infamous quote that anyone who buys a Chevrolet Volt extended-range electric vehicle is an "idiot."

But after sticking to diesel for a long time as its sole green strategy, Audi is now storming ahead into smaller, hybrid, and electric cars with a fierce vengeance, seemingly determined to make up for lost time. Here's our roundup, from smallest to largest.

Audi A1 teased ahead of 2010 Geneva Motor Show

Audi A1 teased ahead of 2010 Geneva Motor Show

2011 Audi A1 design preview

2011 Audi A1 design preview

2011 Audi A1: Modern mini-car

Audi has been teasing its new A1 mini-car with an extended campaign of images, videos, and details dribbled out every few days before its launch at this spring's Geneva Motor Show.

The first concept to preview the A1 dates was the Metroproject Quattro hybrid concept, which dates all the way back to the 2007 Tokyo Motor Show. It was followed by the Audi A1 Sportback Hybrid Concept at the 2008 Paris Motor Show.

The Audi A1, a premium hatchback that competes with the Mini Cooper in three-door, five-door, and convertible styles, will be sold in Europe starting this summer. In December, photos showed Audi's brand spokesperson Justin Timberlake with an A1 in Los Angeles.

U.S. sales possible

Though U.S. sales plans aren't confirmed, the photos spurred speculation that U.S. A1 sales could help Audi meet stringent gas-mileage requirements in the years to come, as well as achieving its goal of beating both BMW and Mercedes-Benz in global sales by 2015.

In Europe, Audi will offer both gasoline and diesel engines from 1.2 to 1.6 liters, along with a mild hybrid version that could return gas mileage of 50 miles per gallon.

The A1 would likely have a 1.6-liter gasoline engine for the U.S. market, perhaps along with a high-performance "S" model producing as much as 200 horsepower.

Below is a video on A1 quality by Werner Zimmermann, chief of Audi quality control. “The smaller size of the vehicle," he says, "does not mean that customers expect anything less than they always do from an Audi.” Earlier Audi A1 videos can be seen here and here.

2010 Audi A3 TDI named Green Car of the Year, 2009 LA Auto Show

2010 Audi A3 TDI named Green Car of the Year, 2009 LA Auto Show

Angular Rear Exterior View - 2010 Audi A3 4-door HB S tronic 2.0T FrontTrak Premium

Angular Rear Exterior View - 2010 Audi A3 4-door HB S tronic 2.0T FrontTrak Premium

Dashboard - 2010 Audi A3 4-door HB S tronic 2.0T FrontTrak Premium

Dashboard - 2010 Audi A3 4-door HB S tronic 2.0T FrontTrak Premium

All-new 2013 Audi A3: Stylish compact sedan

Audi first sold its A3 compact in the U.S. for the 2006 model year. It is now offered with either a 2.0-liter 200-horsepower, direct-injected turbocharged gasoline engine or a 140-horsepower, 2.0-liter clean-turbodiesel TDI model. Both are five-door hatchbacks.

But there's no four-door A3 sedan model, even though its Volkswagen Golf hatchback counterpart is paired with the VW Jetta seda--which is far more popular in the U.S. than the Golf.

Despite the A3 TDI model winning the 2010 Green Car of the Year Award at December's Los Angeles Auto Show, the smallest Audi sells only a fraction of the total of the A4 sports sedan, Audi's most popular model.

And the Audi A3 is now the oldest model in the line; it will have run seven model years in U.S. (and more in Europe) by the time it is replaced two years hence.

Sedan as well as hatch

During last month's Detroit Auto Show, Inside Line reported that the U.S. Audi sales group had persuaded their German overlords to offer the A3 as a sedan as well as a hatchback when a new version is issued for the 2013 model year.

Perhaps they looked at sales of the VW Jetta versus those of the Golf, or perhaps they just shrugged and admitted that U.S. buyers prefer sedans to hatchbacks--in any size.

The new 2013 Audi A3 sedan would likely be restricted to the U.S. market, but like the A1, its sales would help offset the lower fuel efficiency figures from Audi's core A4 and A6 sports sedans, not to mention the brand-new A8 full-size luxury sedan.

Better features, higher price

The 2013 A3 will be based on many of the same components as the next Volkswagen Golf, although the Audi models will offer higher performance and more luxury features.

That matches the current comparison in the States, where the 2010 Volkswagen Golf and Jetta start under $20,000, but the high-level 2010 Audi A3 TDI comes with a higher level of standard equipment and stickers at $30,000.

2011 Audi A8

2011 Audi A8

2011 Audi A8

2011 Audi A8

2011 Audi A8

2011 Audi A8

2011 Audi A8

2011 Audi A8

Audi A8 Hybrid: Large, luxurious, green

While our sister site TheCarConnection got an advance preview of the 2011 Audi A8 in Miami, the latest flagship for Audi luxury sedans made its official world debut at last month's Detroit Auto Show.

The new A8 has a sleeker, trimmer, and more stylish look than the outgoing model, and it's "the first of a new styling language at Audi," according to executives. Its all-wheel-drive will be teamed with dual-clutch transmissions and an entire range of diesel, turbocharged V-6, and V-8 engines.

With a low drag coefficient of 0.26 and an all-aluminum frame, the A8 is designed to maximize fuel efficiency with any engine. But it's still a big car, albeit 7 inches shorter than the long-wheelbase Mercedes-Benz S-Class sold in the U.S.

Hybrid too

But the surprise news at the Detroit show was that Audi is committed to offering an A8 Hybrid as well. Executives released no details of the hybrid A8 model, saying it would be announced later this year, probably at the Geneva Motor Show in March.

But in its zeal to compete fully against arch-rivals BMW and Mercedes-Benz, Audi clearly feels the need for a hybrid version of its full-size sedan.

It would face off directly against the 2010 Mercedes-Benz S400 Hybrid and the 2010 BMW ActiveHybrid 7, two mild hybrids that are both now on sale in small numbers. Their sales are expected to be highest in the hybrid-friendly U.S. market.

Hybrid shared with VW, Porsche?

Audi is thought to be developing hybrid technology in conjunction with Volkswagen and Porsche, who will launch hybrid versions of their redesigned Touareg and Cayenne sport-utility vehicles this year.

Audi's hybrid plans for its sport utilities are a little murkier; now that the Q7 TDI offers clean-diesel fuel efficiency, some reports say the Q5 will be Audi's first hybrid SUV.

The A8 Hybrid may use the same powertrain as the VW and Porsche vehicles, a direct-injected, supercharged 3.0-liter V6 engine built by Audi that's rated at 333 horsepower. A 38-kilowatt (52-hp) electric motor is mounted between the engine and an 8-speed automatic, giving 221 lb-ft of torque--two-thirds as much torque as the engine itself generates.

Unlike other hybrids, the system gives maximum electric assist at highway speeds by shutting down the engine at light load, with all-electric running at speeds as high as 86 mph. The 2011 Porsche Cayenne Hybrid is expected to arrive at dealers late this year.

We'll bring you more details of Audi's expanding hybrid lineup as we get them.

Audi e-tron Concept

Audi e-tron Concept

Audi e-tron Concept

Audi e-tron Concept

Audi e-tron Concept

Audi e-tron Concept

Audi e-tron Concept

Audi e-tron Concept

Audi e-Tron: Tesla fighter

The green Audi that has received by far the most press attention, however, is undoubtedly their e-Tron all-electric supercar.

It may be the first vehicle from a major manufacturer to aim directly at the small niche of two-seat electric supercars, which is now occupied solely by the undeniably fast and smooth 2010 Tesla Roadster and Roadster Sport models.

Launched at last fall's Frankfurt Motor Show as a bright-red electric two-seater based on the R8 mid-engine supercar, and shown again in orange at the Los Angeles Auto Show, the Audi e-Tron concept metamorphosed yet again for the Detroit Auto Show.

Third time's the charm

The latest e-Tron was a stunning silver sports coupe smaller than the previous pair, widely assumed to be a disguised version of Audi's future R4 "smaller" mid-engine two-seater.

It retains Audi's characteristic all-wheel-drive, but makes do with a pair of electric motors--one per axle--rather than the four used by the earlier concepts. As before, the bodywork features carbon-fiber panels to reduce weight (and add to its high-tech street cred).

The taut lines and overall design of the latest Audi e-Tron concept were widely praised at the Detroit show, and it was designated the best concept car of the show by many commentators.

Production: 1,000 cars

Audi officials are said to be serious about producing the e-Tron, but volume will be limited to 1,000 copies--or exactly the number of Tesla Roadsters that have been built as of last month.

The production R4 is said to be based on the same understructure as upcoming replacements for the Porsche Cayman and Boxster, as well as a future Volkswagen sports car previewed by the Concept BlueSport at last year's Detroit Auto Show.