THERE are lots of intriguing features that are likely to draw attention to the new flagship of the Q7 range including its clever bodyroll-countering chassis, seven-seat practicality and sharp Audi Sport styling, but the headline act has to be its all-new engine.

At the heart of the SQ7 is a 4.0-litre V8 diesel that pumps out 320kW and a massive 900Nm of torque but critically, that figure is available from just 1000rpm thanks to an electrically-driven centrifugal compressor that applies positive manifold pressure before a pair of conventional turbos take over higher up the rev range.

With an electric motor spinning the compressor and not an exhaust turbine, the centrifugal impeller reaches 70,000rpm in 250 milliseconds, according to Audi, but don’t be misled because, while fast impeller response certainly reduces the dreaded lag, it does not eliminate it.

No matter how fast a given compressor or supercharger reaches is boost threshold, the extra air has to travel along an induction tract, fill several cylinders, get compressed, vaporise some diesel and burn before any resulting power can be harnessed, but we are still not done.

After that, the resulting energy has to travel across from the torque converter prime mover to the turbine and on to the wheels via the transmission before it can be perceived by passengers as an increase in acceleration.

While that process may take a little less time than it takes to read, it is by no means instant and it is no exception for the SQ7 drivetrain.

Having said that, Audi’s mighty new diesel is the lowest-lag diesel we have tested and although there is minimal hesitation off the line, the acceleration that follows is bountiful, especially considering its 2330kg kerb weight.

With two more conventional turbochargers in full swing and the electric version taking a break, the 4.0 TDI engine generates a whopping 2.4 bar of relative boost pressure and the power responsiveness when on the move is class-leading.

Not only does the SQ7 set a high bar for diesel power, it even manages to trump a few petrols as well and if that wasn’t impressive enough, it ices the compression ignition cake with one of the best diesel soundtracks out there.

Yes, some of that noise is piped in through the sound system as the SQ5 does, but it sounds more honest than its smaller sibling, and standing outside the SQ7 when it accelerates hard in dynamic mode confirms that the majority of its report is real and from the four square tailpipes.

With so much torque so low in the rev range, the SQ7 has very long legs and is capable of eating kilometres with an insatiable appetite but an almost teetotal demand for fuel. We were asking a little more from the SQ7 that regular day-to-day cruising but still managed a fuel economy figure not far from the reported 7.2L/100km.

Straight line cruising is effortless with a silky ride thanks to the standard air suspension and despite the optional 21-inch wheels fitted to our test car, but Audi’s lane-keep assistant is not our favourite of all the car-maker’s versions of the safety tech.

The inconsistent tugging at the wheel followed by very light steering was a constant distraction and forced us to turn the system off and, unless manually switched off, the system remains active even when the most driver-focused Dynamic setting is selected, which we think is an oversight.

But you can forget about all of the driver assistance systems when the road turns twisty because the SQ7 is a surprising beast.

The Quattro permanent four-wheel-drive system shares the massive torque between each corner subtly and mitigates any undesirable or frightening traits such as under- or oversteer. The SQ7 cannot completely hide its bulk but it does a very decent job trying.

Its nimbleness is enhanced by the optional four-wheel steering which shortens the turning circle by a metre at low speeds but sharpens responsiveness and stability at higher speed.

Overtaking is perhaps the SQ7’s party piece which you could argue is an important safety feature as long as you have set a maximum speed warning or limiter. Speed builds incredibly quickly in Audi’s flagship SUV.

The effect of Audi’s brilliant V8 diesel, clever rear-wheel steering, active roll stabilisation and Quattro Sport differential is deeply impressive but the only thing that tarnishes the compelling package is that the latter three of those variant-defining features are optional extras.

The SQ7 costs $153,616 before on-road costs but the Dynamic package takes that price up to $167,116, which Audi says a majority of customers will happily pay, but we feel a model that trades on its sporty characteristics should have the driver-focused kit included as part of the deal.

It’s not the only option that could blow the budget either with $19,500 carbon-ceramic brake kit, 22-inch wheels for $6490, a panoramic roof costs $3990, while an Alcantara roof lining in black is an extra $3400.

The second row of seating is almost the best seat in the house with plenty of space for adults and a gorgeous quilted leather upholstery that had been added to our car. One child would be kept quiet with the $2700 rear seat entertainment pack and a 10.1-inch tablet, but adding an extra tablet costs another $2250. Ouch.

Moving back to the third row is a little snug for adults but perfectly acceptable for smaller individuals. Customers have the option of removing the electrically folding rear seats in favour of a spare tyre.

A tow bar costs $1500 which is a relative bargain and should almost be compulsory because to not exploit the SQ7’s torque by effortlessly hauling something around would be a waste of that monstrous grunt.

The second of our test cars looked fantastic with posh paint, larger wheels and a dusting of other extras but the as-tested price had swelled to $187,886, which is straying into BMW X5 M and Mercedes GLE63 territory.

But let’s not dwell on cost too much because the Australian market has comprehensively demonstrated that it does not mind splashing a dollar on a high-end, high-performance vehicle if it is worth it and the SQ7 is absolutely worth its asking price.

There are faster SUVs but they are far thirstier and can’t offer accommodation for seven seats which puts the SQ7 in a league of its own.

Add to that a handsome look (as long as you throw a few extras at it), quintessential Audi interior quality and design, and all the practicality of the lesser Q7 variants, and you have a deeply desirable all-round package that looks set to repeat the success of its smaller SQ5 sibling.