If the future of motoring is all-electric, Audi's awesome R8 eTron supercar is the shape of things to come. And it's just one part of Audi's tech-tastic Tron range of next-gen alternative-energy vehicles.

We've been out to Berlin where Audi laid on a mix of prototypes and real production cars for us to drive, at least some of which are coming to the UK. There's a bit of something for everyone.

Pure electric super cars, sporty hybrids, micro EVs with funky rotary engines stuck in the boot, even a hatchback powered by carbon neutral synthetic natural gas.

All-electric ubercar

Let's kick off with the best bit, a hot lap in the R8 e-tron. It's a pure electric respin of Audi's mid-engine super car, packed with a pair of 190hp electric motors and truly massive lithium battery pack - more on that in a moment.

Oh, and if you're wondering, sorry, they're not going to sell it after all. So, this is a million-euro prototype we're abusing...all in the name of science and progress, of course.

Let's have a look at what makes the R8 e-tron tick. Audi started with the existing R8 supercar and then pretty much chucked it all out. The body goes from pure aluminium to an impossibly clever mix of alloy and carbon fibre.

R8 e-tron

That includes carbon fibre springs and anti roll bars. Then there's the rear brakes which are brake-by-wire, definitely an interesting innovation.

Big ol' battery

But the big news in every sense is the lithium-ion battery pack. It weighs in at a preposterous 577kg and pretty deftly illustrates the problem with current electric car technology. The batteries are big.

It adds complexity to the R8 e-tron too - there are multple circuit boards and ECUs looking after the pack and the whole shebang needs a high-tech heat management system, too.

R8 battery

The R8 e-tron isn't quite as quick as its petrol-powered siblings. But it still hits 62mph in 4.2 seconds. And the sense of immediate, seamless thrust is something even the mighty new R8 V10 Plus can't quite match.

And if you thought electric cars weren't fun, just check out the video. The R8 e-tron is a riot.

R8

Although Audi originally intended to sell the R8 e-tron, that plan has now been ditched. As fun as it is to drive and as wonderful it is as a technical achievement, that's probably the correct call.

With a realistic operating range of around 125 miles, this pure EV is like all the others – only really suitable as a town car. And that doesn't make sense in the context of a supercar.

What a Wankel

Next up is the first of two Audi e-tron models that are coming soon to the UK. It's the A1 e-tron, a range-extended electric car. The electric bits are pretty straight forward.

There's a 13.3kwh lithium pack and a 115hp motor. That's enough to hit 60mph in under 10 seconds, so the A1 e-tron is no slouch.

A1 e-tron

But the really interesting bit is the tiny rotary range-extending petrol engine they've stuck in the boot. It's a single-rotor Wankel design (yup, the same basic design Mazda sports car are famous for), but it's small enough to squeeze into the spare wheel well.

Anyway, it boosts the A1 e-tron range from 50km in pure electric mode to 250km. Scampering around Berlin with the Wankel engine running, the drone is a little bit annoying.

But there's a good chance that wind and road roar at motorway speeds could drown it out. It'll be interesting to find out.

Plug-in power

On to the A3 Sportback e-tron. Yup, they just keep coming. This is the second Audi Tron model destined for the UK. Rather than a range extended electric car like the A1, this is a plug-in Hybrid.

A3 e-tron

Headline specs here include Audi's 1.4TFSI petrol engine in 150hp trim, an 8.8kwh lithium pack, a 100hp electric motor and a total system power of 204hp.

Audi says the big deal with the A3 e-tron, apart from the puny 35g/km CO2 output (not including grid emissions from charging obviously) is that it's properly sporty to drive.

A3 e-tron

It wasn't quite ready for testing out in Berlin, so we'll have to wait and see.

'G' is for gas

And finally, it's the A3 g-tron. Yup, 'g' as in gas. It doesn't look anything special, but it's a bi-fuelled car that can run on both natural gas and petrol. Except the gas in this case isn't exactly natural. It's synthetised using renewable energy.

It's a bit complicated, but the basics involve splitting hydrogen from water using wind-farm power, reclaiming CO2 from biomass, and cooking the whole lot up into a carbon neutral fuel that you can burn with impunity.

A3 g-tron

Audi has even built a pilot manufacturing plant to produce the gas for Germany. This one isn't coming to the UK, but the idea of carbon neutral synthetic fuels could be very big in future. It's possible to synthesise pretty much any liquid fuel. Maybe combustion cars aren't dead after all.

Audacious stuff

That's a wrap from Audi's Tron event in Berlin. Impressive stuff? Absolutely, especially given Audi is just a single brand within the mighty Volkswagen group empire.

It's also a glimpse of just how much choice car buyers are going to have over the next few years. Things are going to be exciting - and just a little bit complicated!

The Audi A1 e-tron and A3 e-tron are coming to the UK in 2014. Pricing has yet to be announced.