Audi's 'tron' program has been, well, a little confusing over recent years.

Back in the early days it was oh so simple--one concept car, known simply as the Audi e-tron, represented Audi's foray into future mobility.

Since then it seems a dozen models have come and gone, but after presentations galore and a test drive or two at Audi's future lab tron-experience in Berlin, we're happy to report it's all a lot simpler these days.

Well, kinda.

Audi A3 e-tron

Front and center to Audi's 'tron' range of models is one of only two vehicles genuinely confirmed for production.

Both are variants of Audi's latest A3 compact, though each goes about its 'future of mobility' brief in a different way.

The e-tron, as you might gather from its prefix, uses electric propulsion as part of a plug-in hybrid drivetrain. Audi, in both the past and the present, has been skeptical over fully electric vehicles, but the plug-in A3 e-tron seems to be a happy compromize both for the company and the vehicle's eventual buyers.

Audi began its A3 e-tron presentation saying nothing less than "We're proud that it doesn't look like an electric vehicle".

Controversial to some, perhaps, but in our experience electric car enthusiasts are split between those who embrace the weird and wonderful, and those who'd rather fade into the crowd.

Every inch an A3, the e-tron will certainly appeal more to the latter group--only the incredibly eagle-eyed will spot its discrete badging and more heavily-chromed grille denoting its differences from every other A3.

Audi touts it as a vehicle with no compromises--it has performance, efficiency (just 35 grams per kilometer of CO2, on the European fuel cycle), clean electric running and a healthy dose of luxury.

Unfortunately we were unable to drive the A3 e-tron--the car was on display only--but we'll be assessing that "no compromise" claim soon in a more in-depth feature, so keep your eyes peeled.

Audi future lab tron-experience at Berlin Tempelhof

Audi future lab tron-experience at Berlin Tempelhof

Audi A3 g-tron

The second, and so far only other tron model confirmed for production is also an Audi A3.

Like the e-tron, the g-tron's main source of propulsion is a 1.4-liter turbocharged gasoline engine... but that's about where the similarities stop.

The g-tron is Audi's natural gas vehicle. It'll make production, though its U.S. future is less certain.

Initially at least, it'll be demonstrating Audi's new 'e-gas' program in Germany, using CO2 and water to produce a synthetic natural gas which can then be fed back into the nation's gas supplies. This e-gas will be produced in volumes equal to the amounts used in each g-tron Audi sells, effectively making each car cabon-neutral.

If the A3 e-tron is as little different from a regular A3 as possible, you'd not have a chance spotting the g-tron in a crowd.

Even driving it (full impressions will follow in a future report), it felt exactly like every other 1.4-liter A3--smooth, peppy, nicely-built, unmistakably German. It was just a little cleaner than almost everything else in Berlin traffic...

Audi future lab tron-experience at Berlin Tempelhof

Audi future lab tron-experience at Berlin Tempelhof

Audi A1 e-tron

Welcome to the car Audi won't make.

No, seriously. The A1 e-tron program is off, and it's staying off for the forseeable future. Which is a pity, because a brief road test suggested the car had real potential.

Each test car was one of the original Wankel rotary-engined range-extended vehicles which so delighted engineering types on the model's announcement.

The benefit of this type of range-extending engine is smoothness and silence not far removed from an electric motor itself. We experienced the briefest of moments with the rotary switched on and were the car not at idle in a silent parking lot, it would have been hard to notice.

Other than that, the driving experience threw up nothing unexpected. As a prototype it wasn't quite as "polished" as some (well, most) other electric vehicles we've driven, which just makes it even more of a shame that Audi won't produce the car and refine it further.

Once again, we'll have a full driving report on the A1 e-tron soon.

Audi future lab tron-experience at Berlin Tempelhof

Audi future lab tron-experience at Berlin Tempelhof

Audi R8 e-tron

Audi's A3 e-tron might have taken center stage at Berlin's magnificent Tempelhof disused airfield, but it was driving the R8 e-tron around Tempelhof's vast concrete apron that many of us were looking forward to the most.

We expect a few potential owners were looking forward to it too, but the R8 e-tron is yet another model now no longer destined for production. A grand total of 10 e-trons have been made, and that's as many as will ever be made.

And unlike the A1 e-tron, cut down before it reached its prime, the R8 e-tron is as well-finished as any true production car and seriously, seriously fast.

The official word is that Audi simply isn't happy with the progress of battery technology.

While the car's 133-mile range isn't up to Tesla standards, we can't help feeling the world is missing out with Audi's decision not to make the car in greater numbers.

The technology is truly impressive and we've no doubt there'd be a line of buyers waiting to write a check for whatever Audi wanted to charge.

And--you guessed it--we'll have a full drive report on the R8 e-tron soon. We just need to digest the curry wurst...

Audi provided airfare, lodging, meals and refreshments to enable us to bring you this first-person report.


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