DETROIT MOTOR SHOW: Just like an Audi e-tron, only cleaner

Refueling times and range anxiety keeping you from starting an exodus to battery-electric cars?

How about a zero-emission concept car that can be driven for 600km by electric motors, and then completely refueled in four minutes before doing it again?

Enter the four-seat Audi h-tron quattro concept. Heavily based on the Frankfurt show’s e-tron quattro concept, the h-tron quattro concept promises clean, quiet driving, all-wheel drive grip and a 200km/h top speed.

Capable of hitting 100km/h in less than seven seconds, the five-seat h-tron quattro concept will use about a kilogram of hydrogen every 100km.

Its powertrain is a development of the system used in the 2014 A7 h-tron concept car, and uses a 90kW electric motor to drive the front wheels and a 140kW electric motor on the rear axle.

With 550Nm of total system torque, its performance is roughly equivalent to the 3.0-litre V6 petrol and diesel engines in the larger Audi models like the A6, A7 and A8.

Audi is refusing to talk about a production future for its e-tron and h-tron concepts, but both are believed to be headed for production, with the e-tron arriving first in 2018 and closer to 2020 for the h-tron.

Former Audi sales and marketing director, Luca de Meo, said last year that it the production e-tron battery-electric version would cost about the same as a higher-spec A6.

While the h-tron’s fuel cell nominally delivers 110kW of power (to put it in line with Audi’s base four-cylinder petrol and diesel engines), the supplementary lithium-ion battery pack can almost double that on demand, delivering temporary surges of up to 100kW.

The flexible MLB (Modular Longitudinal Matrix) architecture from the latest Audi A7 sits beneath the concept, rather than the Volkswagen Group’s specific all-electric architecture. Audi says the MLB is flexible enough to cope with the big changes it needs beneath the floor, and its structure is more or less identical to the battery-electric e-tron quattro concept.

Unlike the e-tron quattro concept, though, the h-tron’s 1.8kWh battery pack weighs only 60kg and is fed by the hydrogen fuel stack, by regenerating energy under braking, or both.

That’s not its only source of power, though, with Audi filling its roof with 1.98 metres of solar panels to deliver 320 Watts -- enough for a claimed free 1000km of range a year.

All of its motors and its fuel-cell activation is controlled by a new management system that’s geared for efficiency while making the concept retain a slightly rear-drive feel. Quattro all-wheel drive is delivered by the h-tron mounting the single-speed planetary gear sets inside the electric motor housings.

While it’s called 'quattro', the h-tron quattro concept actually runs as a front-wheel drive at low speeds and light throttle openings, drawing all of its power from the battery, rather than the fuel-cell stack. When the battery begins to deplete or the power demand increase, the car starts to push hydrogen through its fuel cell.

The fifth generation of fuel-cell concept from Audi and the Volkswagen Group, it claims to deliver more than 60 per cent efficiency from its 330-cell fuel-cell stack.

The fuel cell operates between 220 and 280 volts and the development from the A7 h-tron has been aimed at improving the diaphragm materials and the gas-guiding bipolar plates to make the stack smaller, lighter and more economical. There is less platinum in each stack, for example, and it has reduced hydrogen consumption by around 15 per cent by moving its operating temperature 15 degrees north to 95 degrees (Celsius).

The fuel-cell stack sits in the h-tron’s conventional engine bay, while the car’s three 700-bar hydrogen tanks (a large one in the traditional transmission tunnel and smaller ones mounted across the car beneath the rear seat and the boot floor) carry 6kg of hydrogen. The tanks have cores made of polyamide and coated in carbon-fibre reinforced polymer (CFRP) and glass-fibre reinforced polymer (GFRP).

While Audi insists it is a concept car, its long-term commitment to genuine zero-emission driving extends to opening a commercial water-to-fuel plant off the coast of northern Germany in 2013, which uses the wind to power electrolysis to split water into oxygen and hydrogen.

At 4.88 metres long, the h-tron Quattro concept is smaller than the 5.05-metre Q7 but longer than the 4.6-metre Q5, effectively providing the layout for the Q6 model line.

It’s also a motor show-friendly 1.93 metres wide, yet only sits 1.54 metres high and still delivers 500 litres of luggage capacity within a set of proportions that hint at the Prologue concept car of 2014, but with far fussier detailing that doesn’t always seem to work.

The car rides on a development of the Q7’s active air suspension system, complete with rear-wheel steering, and rides on custom 22-inch alloy rims and tyres.

The h-tron Quattro also plays host to the next step in Audi’s lighting explorations, with a mix of Organic Light Emitting Diodes (OLEDS), Matrix LEDs for the headlights and the side sills and white daytime running lights. Where the current A8’s Matrix LED package uses 24 pixels, each headlight on the h-tron Quattro concept delivers 420,000 and are capable of playing movies on the road in front of you...

The interior uses ultra-thin (try 1mm) three OLED displays in front of the driver, plus two touch-screen displays, one of which manages the piloted (autonomous) driving set-up.

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