AUDI A6 BITURBO REVIEW
What's hot: Rock-crushing power, but with typical diesel fuel efficiency
What's not: Yup, 650Nm does not come cheap.
X-Factor: A velvet hammer: the fastest diesel-powered car in the country, but with A6 understated lines
Vehicle Style: Premium large sedan
Engine: 3.0 litreTDI Biturbo V6 diesel | Power/Torque: 230kW/650Nm
Fuel economy listed: 6.4 l/100km | tested: Not recorded
This is a story about an engine. Forget about the car - big, stylish and beautifully finished, all premium Audis are 'known quantities'.
But this engine, the 3.0 litre V6 TDI Biturbo, this is really something. With a monstrous 650Nm and 230kW waiting to be unleashed, this is the kind of engine you will want to write home about ("Hey Ma, golden child here, can I borrow..?").
Unfortunately, or fortunately, to buy the engine you've got to buy the car. And there are lots of shekkels involved; lots.
Of course, buy it, take her for a spin, and she'll hate it. Opening the taps on all those Newtons is like opening the gates of hell and staring inside.
Acceleration is more a wallop than a surge. And the gutteral 'basso profundo' growl is like an overdose of viagra... it won't only leave your neck hairs standing on end.
But, of course, any car your Mum hates is just the kind of vehicle you need in the garage. You can tell her that it accelerates to 100km/h in just 5.1 seconds - it's the fastest diesel-powered vehicle in Australia - and she'll hate that too.
Photography by Chris Brasher.
The hi-po oil-burner is the spawn of Audi's Le Mans diesel racer research.
Hitched under the bonnet of the A6 TDI Biturbo are two turbo-chargers connected in series via a vaccuum-actuated turbine-switchover valve. This valve remains closed at lower revs, leaving the small turbo to provide the boost.
That's below 2500rpm. From that point, the valve begins to open and the larger charger spools up, taking over boost duties completely beyond 3500rpm.
To cope with all the physics that then comes into play - shedding heat, damping pulses and vibrations, minimising mechanical losses - Audi has drawn on its TDI race-car research to make modifications to the cylinder-head cooling, the timing and lift of the intake camshafts and valves, and the oil-jet cooling of the pistons.
There also is a special coating on the piston pins to reduce friction and even the water pump and oil pump have been optimised for maximum efficiency.
That's what you've gotta do when you unleash the kind of forces within an engine capable of hammering 650Nm onto the tarmac.
It does this while returning a listed fuel consumption of just 6.4 l/100km (from a big fat car) and CO2 emissions of just 169g/km.
And what happens when it all comes on boost? An almighty Brother Nelson arse-tightening whallop, that's what, and very quickly.
But the sound... my God. It's unlike any other. There is more gravelly edge to it than you'll find in a hi-po V6, and it replaces the mellow undertones of a bellowing V8 with a deep, brittle ill-tempered snarl.
Audi has put a lot of effort into that sound. There is an actuator (a kind of speaker-cone) built into the exhaust system that superimposes an oscillating pattern over the 'natural' exhaust sound to produce something truly intoxicating.
SAMPLE THE SNARL
Buy the A6 TDI Biturbo, and you'll spend your first few weeks taking 100 of your closest friends for a ride just so that you can watch their faces when you bury the shoe.
They'll be equally impressed by the surge of power at any speed. This thing will suck the face off nearly everything you'll meet in a day of driving; whether overtaking or surging away from the line, it simply goes like a shower (I think that's the accepted technical term).
Putting all those angry neddies to the tarmac is an eight-speed tiptronic auto - and not a DSG, presumably because of all that torque. One assumes it's been hewn from a titanium billet to handle the forces being slammed through it.
Otherwise, the drive is typically A6. It's one of the more comfortable in the Audi stable with a very composed ride thanks to that long wheelbase and sensible damping; it can be switched between dynamic (sport), normal and comfort modes.
The Quattro AWD system provides prodigious grip out of a corner, but, having the front wheels sharing the driving effort results in a steering feel that's a little numb compared to (for instance) BMW's rear-drive saloons.
It's a minor compromise you'll be prepared to accept. Something tells me that with all those Newtons waiting to bite the hand, you'll one day appreciate the grip and security of the Quattro system.
INTERIOR AND FEATURES
Can't say I'm too enamoured with the wood-trim inside, but everything else, everything, is superbly finished, feels great, and has the solidity of a brick.
The seats, trimmed to perfection, are broad, well-shaped and comfortable. And aside from that gruff, riotous bellow from under the bonnet, it's otherwise as quiet as Kelly's grave inside.
Wind noise and tyre roar are as good as banished. That's what premium motoring is all about, and Audi's A6 is very good at it.
It's also well-specced; key features being MMI Navigation-plus with a nifty retractable screen and touch-pad, Milano leather, electric glass sunroof, electrically adjustable front seats with memory function for the driver, Bluetooth with audio streaming, Bose surround-sound audio with Audi music interface, rear-view camera and 18-inch alloys.
FIRST DRIVE VERDICT
You'd buy Audi's A6 TDI Biturbo Quattro for the engine alone. It's more than a monster, it's a stampede.
Wrapped in A6 clobber, it's also something of sleeper: only the practiced eye will know what prodigious power and torque is nestled under that big wide bonnet and understated premium-saloon lines.
But, at around $120k, it's one for the few.
We like the A6 in all its variants; if you can stretch your wallet to the TDI Biturbo you won't be disappointed. This car,with this engine, is the absolute embodiment of the iron-fist in a velvet glove.
Photography by Chris Brasher.