Audi decrees death to lag with electrically turbocharged SQ7
As tightening emissions regulations push car manufacturers towards turbocharging across the range, there are two words that make the world's car enthusiasts nervous: turbo lag. Audi thinks it solved that problem with its new SQ7, which packs an electric compressor in with two traditional turbochargers.
At the core of the Q7 S is a 4.0-liter turbodiesel V8, packing 320 kW (435 hp) and a chunky 900 Nm of torque between 1,000 and 3,250 rpm. This translates to a 0-100 km/h (62 mph) sprint time of 4.8 seconds on the way to an electronically limited top speed of 250 km/h (155 mph).
The key to the big Audi's impressive acceleration is an electric compressor placed in air flow downstream of the car's intercooler, nice and close to the engine. The compressor wheel can spin at up to 70,000 rpm without needing exhaust gases to drive it, which means boost is available in under 250 milliseconds at low revs.
The system draws its power from a 48-volt electrical subsystem, specifically designed to support the electric compressor and active anti-rollbars. A 48-volt lithium battery is integrated into the existing 12-volt system through a DC/DC convertor.
There's more turbo trickery in the car's motor to back the electric compressor up. The two traditional turbochargers nestled in the engine's "vee" are arranged sequentially, with exhaust gases flowing through one compressor at low speeds, and the second turbocharger kicking in at higher engine loads. Audi says this provides lag free response all the way across the rev range, and linear power delivery.
Despite its heavyweight performance, the Q7 doesn't drink like one of the big boys, with a claimed combined fuel use figure of 7.4 l/100km (31.8 mpg).
Cars with four rings on the bonnet don't always win accolades their handling prowess, but Ingolstadt's engineers have worked hard to make sure the Q7 can back its big power up with a stable chassis. Although the standard, passive setup should be able to handle itself just fine, we'd be ticking the box to have the car fitted with Audi's networked suspension system, which uses a central controller to manage active anti rollbars, springs and dampers.
The most impressive element of the car's suspension system is the electromechanical active anti-roll system, which has a small electric motor is hooked up to a three stage planetary gearbox. There are two separate sides to the stabilizer, which can be disconnected for a more supple ride on rough roads and then connected and stiffened up when the owner wants to get sporty on a smooth mountain road.
In a move that would look familiar to anyone working at Porsche, the Q7 S has even been fitted with a rear-wheel steering system that can steer up to 5 degrees for a more stable ride at high speed, and a sharper turn-in at low speed. Also contributing to the car's improved handling is an optional sports differential that uses torque vectoring on the rear axle.
With all of this impressive chassis and engine technology you'd think Audi would have gone to town on the car's styling, but as has become standard, the stylists have kept things simple – inside and out. Aside from 20-inch wheels, a unique diffuser and silver mirror caps, the Q7's styling is largely unchanged, while the interior is the same gorgeous, understated design that won us over in Detroit.
All up, the SQ7 will set you back €89,900 (£69,474/US$98,886) before you start ticking boxes on the option sheet.