Hydrogen power technology, and its green motoring prospects, have fallen by the wayside of late in the wake of lithium ion’s growing ‘alt-power’ prominence.
But fuel-cell tech is far from dead. A case in point is the A7 h-tron, Audi’s fourth generation of hydrogen-tech development. Audi’s latest zero emissions powertrain approach has turned away from more traditional liquid hydrogen methodology and towards compressed hydrogen.
And it’s no mere pipedream. During a recent trip to Ingolstadt, Audi flung us the key to one of its A7 h-tron prototypes – road-registered in its homeland – for a surprisingly brisk punt around the Deutsch countryside.
A completely bespoke drivetrain design, the A7 uses four rear-mounted compressed hydrogen storage tanks with the fuel-cell system mounted where the conventional combustion engine is usually located. This all powers two electric motors: one for the front axle, another for the rear.
The downside? Add an 8.8kW/h battery pack and there’s an additional 300kg over a 3.0TDI quattro A7; making the h-tron almost 2000kg. The upside, though, is a nominal 170kW and 540Nm.
It gets better. There’s no transmission, just a fixed single-gear mechanism between the motors and wheels, eliminating parasitic powertrain losses. Better still, each motor can overboost up to 114kW in bursts, creating a 228kW power peak available at the wheels.
Want more? Given the A7’s kerb mass, there’s a crucial 540Nm delivered the instant the electric motors start spinning.
Performance? On twisty back roads there are ample herbs under foot. It’s the sort of energy you might otherwise associate with a healthy turbodiesel. But there’s no rattle on start, no engine thrum on the move.
Sonically, the Sportback is as silent as any other electric car at low speeds. And the compressor could easily be mistaken for the whoosh of a small turbocharger. Top speed, too, is a very handy 180km/h.
Outright performance, though, isn’t the point. It’s more to test if emissions-free electric motoring, with fast refill times, has viability. And more to demonstrate that a fuel-cell motoring experience can feel, to a petrolhead, well, normal.
How normal is it to drive? Put it this way: if you were to guess what powertrain you were driving without prior knowledge, you’d guess it was a turbo petrol with some magical instant torque boost. Or, perhaps, a very quiet diesel. You can’t tell it’s a fuel-cell car.
And if a motoring scribe attuned to dissecting differences in powertrain feel can’t guess, the average motorist will never tell the difference. That, really, is the biggest win for the prototype that emits nothing bar water vapour from its twin tailpipes.
Critical, then, are range and refuelling. And in fourth-gen prototype form, the luxurious, spacious and otherwise compromise-free A7 h-tron offers a 500km range (hydrogen only), an added 50km in full electric mode, and refills its tanks in around three minutes.
Whether there’ll be broader infrastructure in the future to support commercialised fuel-cell motoring, though, is the biggest question mark.
4 out of 5 stars
Engine: 2 x electric motors
Power: 170kW (228kW in overboost)
0-100km/h: 7.9sec (claimed)