Engineers including Sir Alec Issigonis, who once reinvented the Mini Moke as an Arctic exploration device using dual 848cc engines with interconnected throttle cabling, have discovered that two combustion engines in one car is rarely worth the trouble.
Electric motors are proving to be much better suited to this approach, though. They’re easier to package, control and maintain than oily powerplants and offer crushing performance potential when teamed up, which is why spec sheet headliners such as the Tesla Model S and Porsche Taycan have one dedicated motor for each axle.
Independent drive units can also maximise traction or divide their efforts so that neither strays too often from its window of efficiency and therefore saps precious range. And as manufacturers are rapidly learning, control of individual axles can, if your engineers are clever enough, give even the most battery-bloated chassis an intravenous hit of agility.
At Audi, they’re cleverer than most, and so the E-tron S Sportback, seen here as a prototype in light camouflage but due to arrive in the spring, uses no fewer than three electric drive motors. The fastback SUV will be the first S-badged electric car to leave Ingolstadt, with the traditional increases in performance and handling.
Compared with the existing E-tron 55 quattro, whose MEB Evo platform has been carried over, the wheel-and-tyre package has been beefed up, as have the by-wire brakes and the cooling, while the air suspension has been tuned for even closer body control. Expect prices to start beyond £80,000, compared with £59,900 for the E-tron 55.
The biggest difference, however, is the additional electric motor. Instead of one motor driving the rear axle, as found in the E-tron 55, there are two in the E-tron S: one for each wheel, à la Polestar 1, and each with its own single-speed gearbox.
This paves the way for ultra-precise torque-vectoring with, in Audi’s words, a high level of transverse dynamics. Or, in our words, improbably big skids if the car is in Dynamic driving mode with the stability control system set to Sport or, better still, entirely off.
Audi claims this system can distribute torque in a quarter of the time needed by any mechanical counterpart, such as the Sport differential in the new RS6 Avant, and during cornering can feed up to 162lb ft more torque to the outside wheel than the inside – far more than the 10% difference possible with the clutched Sport differential.
Furthermore, the electric torque vectoring system isn’t finally spurred into action only at the very limit of grip, and then with no true control over which direction torque is sent, as is the case with a regular limited-slip differential. In theory, the satisfying sensations of apportioning torque to the outside rear wheel can therefore be felt by the driver at any time.