Audi A7 Sportback h-tron 2015 Review

Zero-emission electric cars will play a role in Audi’s future, the brand hinted during the Los Angeles motor show, but they might not all be battery-electric hybrids. Some, instead, will look like the A7 Sportback h-tron.

The streets of LA probably carry more electric or hybrid-electric cars than any other streets in the world bar Paulo Alto, so it’s not unusual to see cars silently flitting their way through the broad avenues here.

It is, though, unusual to see them doing it without recharging for more than 500km. That sort of range is what Audi’s hydrogen fuel-cell car brings to the table, and it feels extraordinarily complete, especially for a concept car.

Maybe that’s because this is the fourth generation of Audi’s fuel-cell development, which publicly began with an A2 version back in 2002.

Maybe that’s because this powertrain was ready, at this exact stage of development 18 months ago, designed to slot into both the current MLB big-car architecture and the next-generation MLB Evo architecture at the same time.

Or maybe it’s just good.

For all anybody can see from the outside, it’s just another A7, the brand’s droopy-tailed, wide-tracked uber luxury liftback. It has no ride height issues, no odd holes in it for plugs, nothing unusual at all.

It’s a bit the same inside, too. All the width is still there, along with the rear seat that prefers only two occupants and the enormous cargo area remains intact, too.

It also remains a 'quattro', but in an unusual way. There’s its hydrogen fuel-cell stack sitting where the internal combustion engine would normally be and it directly powers the electric motor that drives the front wheels.

Then there’s a plug-in hybrid component to it, with an 8.8kW/h lithium-ion battery pack, taken directly from the A3 e-tron, able to drive an electric motor mounted on the rear differential. Bingo. Instant, computer-controlled all-wheel drive.

Both motors run the same 85kW official power rating (hence the quoted 170kW power figure), but both can be briefly overboosted to 114kW for short bursts, like overtaking or punching off the line.

The combination means the A7 Sportback h-tron delivers 540Nm of torque (each motor is capable of making 270Nm) that arrives instantaneously whenever you touch of the throttle.

It’s an easy car to drive, too. The steering feels the same as the standard A7, though the car feels a touch heavier (because, at 1970kg, it is heavier, but not by as much as you might think). Other than that, the controls are the same, the seats are the same, the climate-control is identical and even the radar cruise control works exactly the same way.

There are good reasons for this, as Audi’s Director of Development, Dr Ulrich Hackenberg, explained.

“Urbanisation is the driver for CO2 regulations. We have a broad portfolio of alternative drivetrain technologies, but it has to all fit with MLB (Modular Longitudinal Basis, which is the chassis beneath the next A6, A7, A8, Q7 and Q8).

“The key to the success of alternative drivetrain technologies in production cars for us is MLB, because we won’t have to invest in specific plants to build the cars. So if volumes aren’t what we expect, we can just turn it to more of what is selling.

“We are in a position to launch the production process as soon as the market and the infrastructure are ready,” he insisted.

“The other key is that alternative drives need to meet our customers’ expectations for drivability.”

So to deliver that driveability, the A7 Sportback h-tron swallows 130 litres (or 5kg, if you prefer) of hydrogen in four tanks, but it only refills via one nozzle and then automatically spreads it around the carbon-fibre-reinforced aluminium tanks.

Again, stuff’s going on there, but it’s not for you to worry about, especially when it refills the 700-bar tanks in three to five minutes, as opposed to a pure battery-electric car’s 'refill', which is measured in hours.

All you have to worry about is plucking Drive and moving silently away. There is no noise, no hesitation, nothing new to learn at all, except dealing with silence.

It trickles out of a driveway just like a battery-electric car, but without even their customary gear whine and bearing noises. There’s just the crunch of stones in the tyres and a very slight hum.

But then you point it at the traffic and watch it fly. Audi has limited the A7 Sportback h-tron to 180km/h, but insists it reaches 100km/h in 7.8 seconds, and that feels about right.

It’s got plenty of pep, with most of its hard work happening early in the rev range before the single-speed transmission begins to get a touch whiny above 100km/h.

Darting in and out of traffic is easy to do, because it is just so strong every time you tap the throttle. Forget its power figure, because it gives its very best work on the torque curve and its available torque curve can be at 100 percent from the instant you touch the throttle. Almost.

One of the reasons Audi has fitted the back-end of this car with the A3 e-tron’s plug-in hybrid battery system is that fuel cells take a fraction of time, maybe a tenth of a second, to deliver the energy the throttle has asked for.

It’s a chemical reaction, after all, and it’s only done on demand. The battery pack, then, can be used to fill in the slight lag in the performance delivery by providing energy to both electric motors until the stack gets on top of things. (Or it can be used to just deliver 50km of battery-electric range, depending on the driving mode and whether the driver wants to save the hydrogen for later.)

The 300-cell fuel-cell stack forces the hydrogen onto an anode, where each atom is broken into protons and electrons, with the protons migrating through the polymer cell membranes to reach the positively charged cathode. There they react with oxygen, are forced as air into the stack by an electric turbocharger, to create water vapour, which is pushed out of the car via a lightweight, plastic exhaust pipe. No rusty or burnt-out pipes here…

The separated electrons, meanwhile, supply the car’s electricity, delivering between 0.6 and 0.8 volts per cell for a system voltage of between 230 and 360 volts, so it can be up to 95 per cent efficient. That stacks up pretty well against the best internal-combustion engines.

The stack is cooled via the same water circuit that cools the DC/AC converter (the battery and fuel cell stack deliver direct current at different voltages, while the electric motors work on alternating current). It is also modular, so it can easily be made to fit in different engine bays and deliver different power outputs.

And it’s all just too easy to get used to, to feel comfortable in. Forget the complications below the floor and in front of the firewall (difficult, because they are legion) and just drive.

It cruises comfortably, with the air suspension taking care of bumps and the extra weight not hurting the ride. It changes direction with a touch less enthusiasm than the internal-combustion version, but then it does only use a kilogram of hydrogen every 100km, so there’s some recompense.

It never gets noisy and there’s no significant gear whine, just road and wind noise and the hushed rush of the electric turbo filling the fuel cell with air.

The trouble is that, right now, it’s going to cost about four times what a battery-electric hybrid will cost and even eradicating range anxiety isn’t going to convince zero-emission fans to cough up that much money.

But that’s today. Audi is already working on the fifth generation of its fuel-cell program and the costs are coming down all the time. They’ll come down even more when they can reduce the amount of platinum they need in the fuel cell membranes, of course, but there are other economies of scale needed, too.

Noise and infrastructure aside, though, it’s a clear sign that there’s a quite pleasant world waiting at the other end of the lifespan of internal-combustion engines. And that if governments keep pushing for zero-emission vehicles, somebody needs to pony up for the infrastructure to bring fuel-cell cars to a wider audience.

After all, storing energy in a battery-electric car is a lot more difficult than just creating it as you need it…