2017 Audi SQ7 TDI: The High-Voltage Diesel SUV
Complexity, Audi is thy name.
Official Photos and Info
Audi’s ultimate hedge against the alternative-fuel future is offering every possible type of powertrain. In Europe, various members of the Audi lineup can run on natural gas, hydrogen, electricity, gasoline, or diesel, and there are all sorts of hybrids across varying body styles. The brand’s latest entry is a high-performance diesel SUV, the SQ7 TDI, which blends proven, decades-old technology with a complex, state-of-the-art forced-induction system. Admit it, your mutual funds aren’t this well diversified.
Before we go any further, know that Audi is committed to bringing this diesel ute to America—and ensuring it is squeaky clean per EPA regulations. Well, eventually. (The official line from Audi USA: “It has not been approved by the board, but we are optimistic.”) The moratorium on sales of the Volkswagen Group’s diesel vehicles is still in place as of this writing, and potential fines and the results of ongoing litigation remain unknowns, but that doesn’t mean diesel is dead here. Besides, Audi wants to show Americans it has more to offer green-leaners than
the plug-in-hybrid A3 e-tron and the Q5 hybrid. Like, for instance, a seven-passenger SUV with 664 lb-ft of torque.
Electric Superchargers and 48-Volt Electrical Systems Have Arrived
We’re fans of
the all-new Q7, as evidenced by
its comparison-test victory against the Volvo XC90, BMW X5, and Range Rover Sport. For now, the regular Q7 offers only a supercharged 3.0-liter V-6 with 333 horsepower and 325 lb-ft of torque. While that engine is strong and refined, the SQ7 TDI looks to build on the Q7 experience with stupefying levels of speed and efficiency.
The SQ7’s 4.0-liter diesel V-8 makes 435 horsepower and 664 lb-ft of torque between 1000 and 3250 rpm by employing two turbochargers as well as, for the first time ever in a production car, an electric supercharger. Audi demonstrated this setup on
an RS5 TDI prototype we drove in 2014, and the long-awaited promise of turbocharged engines with zero lag may finally be here. Unlike a conventional supercharger, which is powered via a pulley attached to the crankshaft, Audi’s electric unit is spooled by a 7-kW DC motor essentially taking the place of a turbocharger’s turbine. The motor is connected to the compressor via a shaft, and it’s neither exhaust-driven like a turbocharger nor crank-driven like a supercharger. It can spin up to 70,000 rpm in less than a quarter of a second. This kind of power draw would be too taxing to a traditional 12-volt system, so the SQ7 TDI also is fitted with a 48-volt lithium-ion battery under the cargo floor that can output up to 13 kilowatts of electrical power at a moment’s notice.
Audi connects the 48-volt subsystem to the standard 12-volt system (which uses a conventional lead-acid battery) via a DC-DC converter and a 3-kW generator. Here, as opposed to diodes converting AC to DC current, a metal-oxide semiconductor field-effect transistor (or MOSFET, same as the semiconductors working wonders on your computer’s motherboard) handles the job with greater efficiency. The 48-volt battery also reduces the 12-volt system’s load at varying times.
This is a hyper-complicated way of saying the SQ7 TDI’s supercharger requires no engine power to deliver full boost. As engine speeds increase, sequential turbos take over. Each is fed by one exhaust valve of each cylinder. At low rpm, only one turbo spins as half the valves remain closed. As engine speed rises, the other valves begin to operate as normal, feeding the other turbo exhaust energy, and the electric supercharger is no longer needed. The eight-speed automatic gets sportier programming, too, with Audi predicting a zero-to-62-mph time of 4.8 seconds and a governed top speed of 155 mph. Your eyeballs are probably out of breath at this point, but hang in there.
The Handling’s Electric, Too
You may be wondering what else Audi uses those available 13 kilowatts from the 48-volt battery to power. Well, it also delivers juice to the active anti-roll bars, which Audi elegantly calls “electromechanical active roll stabilization.” In principle, they’re not much different from a hydraulically actuated active anti-roll-bar setup, in that they can quickly stiffen the bars to reduce body roll in hard corners or loosen them for comfort during straight-line cruising. But Audi’s anti-roll bars take after those used in
the new Bentley Bentayga, which splice an electric motor and gearset between the two ends.
Of course, Audi claims the high electrical current makes its active anti-roll bars quicker to respond, including at low speeds. Four-wheel steering (the rear wheels can turn up to five degrees) and a sport-tuned adaptive air suspension are standard, while a torque-vectoring Quattro sport rear differential is optional. Given the 285-section-width tires, and especially when outfitted with optional carbon-ceramic brakes, we expect no less than thoroughly scintillating dynamic performance for a vehicle this size.
It Gets Simpler From Here On Out
As a card-carrying member of Audi’s S model lineup, the SQ7 TDI’s visuals are pretty discreet. The side mirrors wear the usual silver caps. The trapezoidal grille, flanked between LED headlamps with “double arrow” running lamps, is painted matte gray to match the rear “underbody guard.” The spidery 20-inch wheels (22s are optional) are gray. The quad-tip exhaust is the key tell, outside of the badges. How does it sound? The SQ7 mounts external speakers by the tailpipes—yes, we’ve come to that point—to wash out the diesel clatter. We heard it on the RS5 TDI, and the effect there is (almost) like revving an RS7.
Analog gauges with gray faces, a flat-bottomed steering wheel, aluminum pedals and trim, diamond-stitched leather seats, and microsuede on the door panels and headliner complete the S trimmings inside. Brown leather and copper-woven carbon-fiber trim are among the many upgrades, including a 1920-watt Bang & Olufsen audio system.
The SQ7 goes on sale in Europe this spring, but U.S. timing, pricing, and fuel economy are currently unknown. We’d give you the European figures, but they’re essentially worthless given the major differences in pricing structures and efficiency test cycles. Once the diesel smoke clears and Audi can move its grounded inventory, expect the SQ7 TDI (and perhaps
the plug-in Q7 e-tron TDI) to hit our shores. We look forward to it.
