If we went through each of the SQ8's cutting-edge systems we’d have to write a book, so we'll keep this simple and highlight the most important bit: its 48v electrical system. Also seen on the closely related Audi SQ7 (the SQ7 is currently off sale but due to be re-launched shortly), its gift to this SUV’s searing performance is the electric compressor it supports. Like the two normal turbochargers this boosts the power of the 4.0-litre V8 diesel but, being electrically powered, it works near instantaneously.
That helps to overcome a common complaint about turbocharged engines: the delay between pressing the accelerator and receiving full power – commonly referred to as turbo lag. Does it work? Yes. Because of the SQ8 is more responsive than its rivals from low engine revs and a devastating overtaking machine. Blessed as it is with 663 lb ft of torque — the most shove of any SUV currently on sale — means it's also effortless to drive, but when you do stretch its legs it's quicker flat-out than a BMW X5 M50d. The Porsche Cayenne Turbo is considerably quicker still, though.
If you’re searching for a sports SUV that will be comfy enough for a daily commute, the SQ8 is a strong candidate. As well as the electric compressor, the 48V electric system also controls the clever active anti-roll bars; in layman's terms, these limit body lean in corners without (supposedly) compromising the ride quality over bumps.
They work with the standard air suspension, which you can stiffen or soften depending on your mood, but even in its softest mode the ride is firm, at least compared to a regular Q8. But for a sporty SUV it's acceptable and very well damped, remaining utterly composed over the kind of repetitive bumps that would otherwise have you bouncing out of your seat.
All-wheel steering – standard on Vorsprung models – is particularly useful at low speeds, such was when navigating a multi storey car park; it relieves a lot of effort by reducing the Q8's turning circle. It's hard to notice any effect at motorway speeds, though. Also standard on Vorsprung models, the "sport" rear differential can apportion power between each rear wheel to maximise traction when exiting a corner or accelerating hard. However, while a desirable feature on a sports car, it's not especially worthwhile on a 2.4-tonne SUV.
After all, even with such clever kit fitted, the SQ8 doesn’t egg you on to drive spiritedly in quite the way a Porsche Cayenne does. Of course, because no big, heavy, sports SUV — including the Cayenne — will handle as nimbly as a sports car, but the SQ8 isn't as much fun as the Porsche. Sure, its precise steering and tight turn-in give you great confidence when entering a corner, but the Porsche Cayenne is more engaging at similar speeds and remains our go-to choice if you’re looking for the best-driving SUV of this size.