Audi’s biggest S model digs deep into its technical arsenal to create a talented, if somewhat joyless SUV, but then aren’t they all?
The Audi SQ7 has been lording it over private school car parks since 2017 with its V8 diesel engine and obnoxious styling, but alongside the Q7 range for 2020, the range-topper has undergone a substantial mid-life update focusing on styling, tech and an all-new interior.
The powertrain is unchanged, mind, and as one of the few models within the Volkswagen group still available with the techy mild-hybrid twin-turbocharged V8 diesel engine, the SQ7 has suddenly become a unique entity within its Volkswagen group parent company, which so often offers variations on a similar theme.
So as a technical flagship, luxury car, performance-oriented SUV and family hauler the Audi SQ7 TDI promises everything. But can it deliver?
Performance and 0-100kmh
For the SQ7’s 4-litre turbocharged V8 diesel to propel the leviathan that this Audi is, it needs to produce some equally enormous figures. Thankfully it does. The SQ7’s diesel makes 429bhp from 3750 to 5000rpm. But that’s not as impressive as the amount of torque it produces – 664lb ft from a ludicrously low 1000rpm. So despite weighing 2330kg, which does seem fitting for its immense size, it can reach 62mph from rest in 4.9sec – that’s over half a second quicker than an F-type convertible, albeit it a four-cylinder one. The SQ7’s top speed is limited to 155mph.
The SQ7 doesn’t just perform like a petrol SUV, it behaves more like one, too. Diesels, typically, don’t respond well to being revved; changing up halfway through the rev range to utilise their torque often seems most effective. The SQ7’s sequential turbochargers make the diesel V8 far more entertaining to drive all the way to the red line. You get real, responsive performance close to the 5000rpm rev limit.
With the SQ7’s engine in Dynamic mode it’s as raucous and as brash as you’d want your performance SUV to sound. And at anything other than idle you could be forgiven for thinking it was a petrol V8 from within the cabin. The sound from outside isn’t as bombastic, but the deep burbling you do hear is pleasant and befitting of the remarkable performance. The biggest problem is that it sounds so good, and the noise disguises what fuel it’s running on so well that a 5000rpm rev limit almost feels too low.
Engine and Transmission
There is a lot of impressive technology in the SQ7, but the engine is one of the most remarkable things about the entire car. At its core it’s a 3956cc, 90-degree, diesel V8 with double overhead cams and four valves per cylinder. It also has three compressors – one electric supercharger, and then two turbochargers placed within the two cylinder banks.
Let’s start with the headline-grabbing electric supercharger. This supplements the additional twin-turbo set-up by forcing the air from the intercooler into the inlet. The electric compressor works when the engine is at low revs and the conventional turbos aren’t spinning fast enough. At around 1400rpm the other turbos start to work, and eventually the electric compressor is bypassed so as not to interrupt faster moving inlet gases. The electric supercharger means the engine can develop maximum torque of 664lb ft from 1000rpm and helps eradicate turbo lag at low revs.
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The SQ7’s two other compressors, the turbochargers, work sequentially to create a progressive power delivery. As the revs increase, the first turbo starts to boost along side the electric compressor before it is bypassed. Then, at higher revs, the first turbo is joined by the second to help make more power.
This is nothing new, but the way the second turbo is activated is far more interesting. Each of the two exhaust ports per cylinder feed separate turbochargers; one port sends gases to the first turbo while the other port sends gases to the second turbo. This is achieved by keeping the valve to the second port closed at low revs, essentially making the engine a three-valve-per-cylinder single-turbo engine until the revs are high enough.
Audi has used its valve lift system (AVS) to achieve this. In most applications, AVS switches between two cam profiles to help increase performance at high revs while maintaining drivability at lower rpm. However, in the SQ7’s engine one of these cam profiles keeps the valve completely closed, then, when the second profile engages, the valve begins to operate and exhaust gases flood to the second turbocharger.
Both of the turbos are nestled within the two banks of cylinders, making the SQ7’s diesel a hot-V engine. This is essential to be able to feed two turbos with individual exhaust ports, but this configuration also helps heat up the catalytic converters rapidly, making them able to work sooner. The hot-V set-up also means that the entire engine is more compact, allowing it to be used in multiple different chassis.
A triplet of compressors, all working in stages, might sound incredibly complicated, but in reality it’s very effective. The electric compressor really does create an immediate throttle response at low revs. However, it really is only the very first time you stand on the accelerator that it feels truly impressive because the instant response is just so incredibly easy to get used to. As the turbos overlap to keep the inlet pressures high, there is a slight surge at around 2800rpm, but that’s the only slight deviation away from linear power delivery.
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The SQ7’s power is sent through an eight-speed automatic. Yes, it’s the same ZF unit that’s in, well, everything. But, why not, when the shifts are as smooth and effective as they are in the SQ7? It isn’t at its quickest in this big Audi, but with 664lb ft to deal with that can be forgiven.
Ride and Handling
The engine isn’t the only part of the SQ7 that’s stuffed with new technology, as the chassis is similarly high-tech. The SQ7 can be equipped with Audi’s sport rear differential, rear-wheel steering and an electromechanically supplemented anti-roll bar.
The sport differential works in the same way as the ones we’re familiar with in some other performance Audis, but it’s the first time it’s appeared in a Q7. Audi’s sport diff is similar to a conventional limited-slip diff. But, rather than torque input dictating the amount of lock the clutches generate, a computer decides. This means that it can distribute torque across the rear axle to increase agility. To add to this nimbleness, the rear wheels can turn by as much as five degrees, too.
Body roll is kept in check by an electric motor and gear set embedded in the centre of each of the anti-roll bars. The motor can deploy up to 885lb ft of torque to stiffen up the ARB further and reduce body roll. With the motor relaxed, it creates a more comfortable ride. Both the front and rear ARB are equipped with this electromechanical device, and so the SQ7’s balance can be altered instantly depending on which driving mode the car is in and how it’s being driven.
All of this technology to aid the chassis and enhance the engine means that Audi has had to fit an extra 48V electrical subsystem to the SQ7. The anti-roll bars and electric engine compressor require so much power that to supply them an ordinary 12V system would require thick, heavy cables. Instead, an entirely different 48V circuit has been added, including another lithium-ion battery in the boot. This is in addition to an ordinary 12V battery that feeds the headlights, infotainment and other minor accessories.
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Just as the innovative engine technology creates a competent and enjoyable powertrain, the sophisticated chassis does the same for the way the SQ7 drives. It feels amazingly agile for its size and set in Dynamic driving mode it responds immediately and faithfully to steering inputs, allowing precise placement on the road. There’s an incredible amount of grip too, so the SQ7 will maintain your desired line and respond well to over-zealous steering inputs.
Once you realise that the SQ7 can be cajoled briskly down a road without any nasty dramas, your confidence grows and a different driving style actually changes how the Audi reacts. Start to trail-brake slightly, treat it more like a grown-up hot hatch, and its dexterity seems to increase even more. What it’s capable of, what it will cope with without becoming flustered and the speeds at which it will corner are truly remarkable for a 2.3-ton car, let alone a high-riding SUV.
With the chassis in Dynamic mode, the ride is good, although Comfort or Auto offer the most comfortable options. In Eco mode there’s slightly less engine vibration transmitted into the cabin, but the big Audi always feels refined.
The top-of-the-range SQ7, the Vorsrpung Edition, comes on huge 22-inch wheels. And, although there are no other mechanical changes, the big rims badly affect the way the SQ7 drives. The ride, which is pleasant with the standard 21-inch wheels, becomes harsh, and over rough tarmac it thinks it’s struggling to find traction. With traction control left on, the ESP light flashes when you put your foot down on craggy roads (like many found in the UK) and the acceleration is muted. Turn off the driver assistance systems as much as possible (they can’t be fully switched off) and the car finds grip and it pulls with the same serious determination as it does on smooth roads or with smaller wheels.
As good and as competent as the SQ7 is when equipped with all that technology and the smaller wheels, you never feel genuinely involved when driving it. You can marvel in its abilities, but you, the driver, never feel as though you have contributed to its agility.
The SQ7 is undoubtedly impressive. It goes well, it’s remarkably nimble, it has exceptional grip and its engine is incredibly effective for the role it’s designed to do. But, at its very best, it isn’t exciting.