Audi A8 vs BMW 6 Series

What's the difference?

The Audi A8 swims in a luxury car shark tank where those paying the big dollars expect top-shelf everything. It delivers a serene driving experience whether you’re in the front or the back, in a superbly engineered and executed luxury sedan package. Not perfect, but very, very impressive.

This isn't a car for everyone's tastes, but if you fit in to the buyer group that just doesn't really know what they want in a luxury car, it could be the perfect fit for your family. The 6 Series GT is a practical large prestige car, albeit one that will likely find very few buyers.

The A8 is close to 5.2 metres long, yet instantly recognisable as an Audi thanks mainly to its evenly weighted proportions, gently curved roofline and overall high-waisted design. Worth noting its drag coefficient (Cd) is an impressively slippery 0.25.

The characteristic look is accentuated by the brand’s signature, six-sided grille, in this instance highlighted by a matrix of high-relief chrome accents. And typically angular LED Matrix headlights sit either side.

Check out our video review for the carefully orchestrated animation they run through when the car is unlocked.

The car looks equally svelte and contemporary from the rear, with just the right amount of chrome lifting the tone and multi-spoke 20-inch rims filling the wheel arches nicely.

As you’d expect, the top-shelf look and feel continues inside with the seats trimmed in aniline leather, perforated on the front and outer rear positions, with genuine hide also covering the centre console, door rails and armrests, steering wheel and upper dashboard.

Fine grain ash wood inserts sit alongside brushed metal elements and a meticulous attention to detail is obvious… everywhere.

For example, the interior door handle design has been thoroughly thought through, requiring a simple underhand tap to open the door, rather than the more conventional, and ergonomically convoluted, ‘over the top’ movement.

Three sleek screens dial up the tech - a 10.1-inch multimedia interface at the top of the centre stack, an 8.6-inch display below it for heating and ventilation, and a 12.3-inch version of Audi’s ‘Virtual Cockpit’ in the instrument binnacle.

And the spacious rear is the epitome of cool, calm Teutonic form and function. You feel relaxed the moment you get in, and isn’t that the primary aim of a car like this?

There is no denying the 6 Series GT looks better than the old 5 Series GT. It isn't as frumpy, it looks more sporty, and to me it appears to have grown into its identity with more conviction than its predecessor.

That said, I don't necessarily like the look very much - it's a bit like a BMW X6 that has been rounded off a little and lowered down substantially. But I can appreciate some of the finer design aesthetics that it offers up: the frameless windows are a nice touch, and the swooping roofline looks smoother than a duck's back.

Other things like the active grille shutters and the air breathers ahead of the front doors are nice functional touches, and to my eye it lives up to BMW's hope of it looking "smooth but muscular". You can get the 630i with either the M Sport package, like you see here, or the more sedate Luxury Line, which is, well, more luxurious looking.

The M Sport styling and equipment package you see in the images here - with M aero kit and 19-inch wheels (ours had been upgraded to optional 20s) - help out with the athletic look of this very big vehicle.

It's huge in fact. The length of the 630i is 5091mm long, it measures 1902mm wide and sits at 1538mm tall, with a lengthy 3070mm wheelbase.

All that equates to a lot of room in the cabin, and what a sumptuous and delightful place it is to be - leather, wood and plush finishes abound.

Space is luxury, be it a large house, a first class seat or a spacious car, and at nearly 5.2 metres long with a close to 3.0m wheelbase the Audi A8 measures up. 

Even before you get in, the doors have an amazing sense of solidity and quality. It’s like opening and closing a bank vault… if that huge circular door had a power-assisted soft-close function. 

There’s copious amounts of space for the driver and front passenger with lots of storage including a lidded box between the front seats, complete with a two-piece longitudinally split top design, so you can sneak your half’s open without displacing your neighbour’s elbow.

The door bins are decent but there isn’t a specific cut-out for bottles, so it’s more a case of laying them down than standing them up. There’s also a handy covered cubby at the end of the door armrests.   

The glove box is a good size and there are two cupholders under a pop-up cover in the centre console.

Of course, the back is where space really counts, and there’s as much room as you’d find in, well… a limo.

Sitting behind the driver’s seat, set for my 183cm position, I enjoyed copious amounts of head, shoulder and legroom. 

There are electric sunblinds for the rear and rear side windows, controlled by buttons in the door as well as the rear seat remote, a 5.7 inch OLED display housed in the beautifully trimmed fold-down centre armrest (which also has a soft close function!). The remote also allows adjustment of the lighting and climate control. Classy.

There’s a shallow storage box and twin cupholders in the armrest, medium size door bins and hard shell pockets on the front seat backs. The rear armrests also feature a small lidded cubby. 

In terms of connectivity and power options there’s wireless Android Auto and Apple CarPlay, a USB-A and USB-C in the front, and an identical pair in the rear, as well as a 12-volt socket in the front and two in the back.

Boot volume is a useful 505 litres (VDA) and the lid is electric, with gesture control. It’s able to easily swallow our three-piece luggage set or the bulky CarsGuide pram. And while the rear seats don’t fold there’s a ski port door to accommodate long items. Just make sure you use the tie-down anchors in the boot to ensure they’re properly secured. There’s a handy netted section behind the left wheel well and a cargo net is included.

Maximum towing capacity, for a braked trailer, is 2.3 tonnes (750kg unbraked) and in more good news, the spare is a space-saver rather than the increasingly prevalent inflator/repair kit.

Now, I said before that this is a bit like an X6, but it has heaps better interior space than that SUV.

As soon as you slide into the driver's seat, you feel like your inside a large car. The cabin space is plentiful, and there's an abundance of storage on offer, too: there's a split-lid armrest between the seats, a pair of cupholders, a phone storage nook with wireless charging, and big door pockets with bottle holsters.

In the back you have access to door pockets, a flip-down armrest with cupholders (that middle part of the seat can fold down completely to allow storage of longer items), and there's excellent room on offer. How many seats in the BMW 6 Series GT? Five - like, five full-size seats.

Because the roofline doesn't rake as sharply as a four-door 'coupe', headroom is excellent for adults (even of the 183cm variety, like myself), and legroom and toe room are equally very good. This is bigger in the back than a 5 Series, but maybe not as plush as a 7 Series… so I guess it makes sense numerically for its nomenclature.

Of course you get climate control in the front (and in the rear if you option it), and the materials are excellent. The media screen is tablet-style, proudly displaying 10.25 inches of high-def real estate that is both touch-capacitive and controllable by way of the central rotary controller with touchpad. And get this - you can even use gestures to control certain elements like volume, swiping and changing tracks… but you have to option that.

The fully digital instrument display is bordered by a set of incomplete dial rings, which is just odd. BMW, back yourself - your buyers can handle just having a digital screen in front of them, particularly when it's as good as this one.

This grandiose hatchback's boot is commodious - with the back seats in place it has a huge 610 litres of cargo capacity, which extends to 1800L with the 40/20/40 seats folded down using the quick release levers in the boot area.

There is no spare wheel (the BMW range is fitted with run-flat tyres) but it does have a secondary hidden storage area under the boot floor for hiding items or stowing wet gear, bathers/swimmers or muddy clothes.

For context, the X6 has 580L seats up, 1525L seats down.

The BMW 6 Series Gran Turismo range starts off with the model tested here, the 630i. It has a list price of $123,500 before on-road costs - and that's whether you buy the M Sport Line or the Luxury Line.

That's quite a lot of money. And while it has a lot of equipment to help justify the cost, the smarter dollars will probably find their way to a more affordable 5 Series.

Standard gear in this spec includes adaptive air suspension with multiple drive modes, a colour head-up display, semi-autonomous parking, adaptive cruise control with steering assistance, auto high-beam LED headlights with LED daytime running lights, DAB+ digital radio, a 16-speaker harman/kardon sound system, a 12.3-inch driver information screen and a 10.25-inch media display with sat nav, Bluetooth and 'BMW ConnectedDrive' online services.

Hey, you even get a panoramic sunroof as standard! Plus there are things like an active rear spoiler, two USB ports and four 12-volt outlets, leather trim, heated front electric seats, electric steering wheel adjustment, keyless entry, push-button start, and an automatic boot.

It also comes loaded with active safety assistance functions - we'll get to that in the safety section below.

Things it's missing at this price point? Well, heated seats are an option, but bundled nicely into the 'Comfort Package' ($3000) which was fitted to our car. The pack includes heated seats front and rear, quad-zone climate control, electric sunblinds for the rear side windows, and electric seat back adjustment. Oh, and BMW continues to gouge consumers $623 for Apple CarPlay (which seemingly didn't work in our car).

The only other 6 Series GT model available is the 640i xDrive, which is again available with the choice of M Sport or Luxury body styling. It's also pretty exxy, with a list price of $148,900, but gets a more performance-focused drivetrain, as well as extra equipment: essentially the Comfort package, plus vented front seats, interior fragrance (eight options), memory settings for the front seats, 20-inch wheels and metallic paint.

Plus the 640i has Sport+ settings - it's probably the wrong car for those - and 'Integral Active Steering' to couple with the all-wheel drive system.

The Audi A8 50TDI is powered by a 3.0-litre turbo-diesel V6 engine sending 210kW (from 3500-4000rpm) and 600Nm (from 1750-3250rpm) to all four wheels via an eight-speed automatic transmission (with ‘Tiptronic’ sequential manual shift function) and Audi’s quattro constant all-wheel drive system using a self-locking centre differential.

It also features a 48-volt electrical set-up for mild hybrid functionality built around a belt connected starter/generator, AC to DC converter and a 48-volt lithium-ion battery. 

With energy recovery of up to 12kW from regenerative braking, it enables the A8 to regularly coast with the engine switched off and helps the extended stop-start system to operate smoothly. 

Under the bonnet of the 630i is a 2.0-litre four-cylinder turbocharged petrol engine, which produces 190kW of power (at 6500rpm) and 400Nm of torque (from 1550-4400rpm). It uses an eight-speed automatic transmission, and is rear-wheel drive.

That may not seem a lot considering the size of this machine, but consider that some of the steamiest four-cylinder hot hatches have nearly the same outputs, and you realise this engine offers up a far-from slouched approach to propulsion.

The 640i xDrive has a 3.0-litre six-cylinder turbocharged engine with 250kW of power and 450Nm of torque. It gets the same eight-speed auto, but as the xDrive naming indicates, it's all-wheel drive.

But this is the one you'd prefer if you want to hit highway speed in a hurry - the 0-100km/h claim is 5.3 seconds, where the 630i takes a full second longer (6.3sec) according to the company.

Audi’s official fuel economy number for the combined (ADR 81/02 - urban, extra-urban) cycle is 6.6L/100km, the 3.0-litre turbo-diesel V6 emitting 175g/km of CO2 in the process.

Over a week of city, suburban, and some freeway running we averaged 11.1L/100km, which is acceptable for a 2.1-tonne luxury sedan.

Also worth noting the standard stop-start system works beautifully thanks to the 48-volt starter/generator.

You’ll need 82 litres of diesel to fill the tank and using the official number, that translates to a range of just over 1240km, which drops to around 740km using our real-world figure.

BMW claims fuel use of 7.0 litres per 100 kilometres, and you'll need to use 95RON premium unleaded when you fill up.

On my trip with the car, I saw about 9.0L/100km across mostly high-speed driving - some freeway, some highway, some country back road touring, and quite a bit of corners and city stuff thrown in as well. I think that's pretty respectable.

What wasn't so great was the lack of premium fuel in some of the 'away from civilisation' places on my route home. Keep that in mind if planning your own GT long-distance cruise.

Despite extensive use of aluminium in the ‘ASF’ platform and body panels, the A8 tips the scales at a sturdy 2095kg, yet Audi says the A8 will accelerate from 0-100km/h in just 5.9 seconds. And with 600Nm of peak torque available across a flat plateau from 1750-3250rpm this big four-door gets up and goes hard when asked to. 

At more sedate speeds you’re occasionally reminded there’s a diesel engine under the bonnet, with that characteristic engine and exhaust noise only making their presence felt under pressure. 

In fact, under normal circumstances, noise, be it the engine, tyres or wind is minimal, thanks to a combination of the car’s aero-efficient shape, thick acoustic glass and other sound-deadening measures throughout the car.

The eight-speed auto transmission is suitably smooth, with the central shifter or wheel-mounted paddles able to make snappy sequential ‘manual’ shifts.

There are four drive modes in the ‘Drive Select’ system - ‘Comfort’, ‘Auto’, ‘Dynamic’ and ‘Individual’ - enabling tweaks to the steering, transmission, throttle and suspension. Comfort felt most appropriate most of the time, although dialling up the throttle and transmission to more aggressive modes in Individual adds an enjoyable edge.

The suspension is five-link front and rear with an adaptive air system smoothing even high-frequency bumps and ruts amazingly well.

Push into a corner and the A8 feels nicely balanced, its wide track, sophisticated suspension, plus the quattro AWD system seamlessly distributing drive between the front and rear axles, keeping the big body under control. In fact, you feel the ‘big car shrinking around you’ syndrome from the get-go.

The steering is precise without being overly sharp and road feel is good. Again, with that 2.1-tonne kerb weight in mind, braking is appropriately powerful with big ventilated discs front (350mm) and rear (330mm).

It pays to remember the turning circle is 12.5m, and it’s worth picking your spot for a U- or three-point turn.

Although there’s a lot going on for the driver in terms of screens, buttons and switches it all makes sense ergonomically. The head-up display is helpful and there’s a common sense mix of digital and physical controls, the latter including an audio volume knob. Yes.

I'll put this out there - if you like to drive, there are BMW models for less than this one that will put a much bigger smile on your face. Like, a 440i Gran Coupe, or even just a 330i sedan…

But if you're in BMW's target market - that being older executive buyers who want space and luxury as a priority over thrills at the wheel, you could do a lot worse.

That's because the 6 Series GT lopes along the highway without fuss - the engine easily coping with the demands of overtaking moves, the adjustable drive modes allowing a light steering and wafting suspension feel to wile away the kilometres.

There are 'Comfort' and 'Comfort Plus' modes, but the latter is a bit too spongy and can be boaty feeling. The Comfort setting is made for the highway.

It is actually pretty agile for its dimensions.

If you decide to deviate from the straight sections, you'll be able to explore a little bit of dynamic range, especially when you dial up the 'Sport' mode, which changes the damper settings, steering weight, throttle and transmission response, and even the digital dials in front of the driver to a more aggressive look.

Our car had the 'Integral Active Steering' setting, which is a variable ratio steering system that includes rear steering - that essentially helps make is more turnable in corners at highway speed, and easier to park at lower speeds. It's difficult to say whether the assistance is excellent or not short of driving a car without the tech, but to this tester it was hard to hide the size and weight (1835kg kerb weight) of the vehicle.

That isn't to say it's clumsy or lumbering - it is actually pretty agile for its dimensions, though it makes a lot more sense on long drives and coastal cruises than it does in the narrow and twisty alpine roads of the Snowy Mountains Highway that I tested it on.

There's good grip from the tyres, and strong response from the powertrain - but if it were my money, and I had to have a 6 Series for whatever reason, I'd be looking towards the 640i model, which has a thumping six-cylinder with 250kW/450Nm - certainly an engine that would be more at home in this car. Plus that model comes with AWD.

The BMW 6 Series GT range has a five-star Euro NCAP crash test score based on 2017 testing, but it hasn't been scored by ANCAP.

There's the usual array of airbags - dual front, front side, full-length curtain and driver's knee airbags are included, plus parking sensors all around, and heaps of safety tech including the 'Driving Assistant Plus' package with lane departure warning and lane keeping assist, forward collision warning, auto emergency braking (AEB) front and rear, blind-spot monitoring and rear cross-traffic alert, and adaptive cruise control with stop and go.

That's all great stuff, and so is the 360-degree camera system with adaptive display - so, if you're reversing and you turn the wheel to one side, the image on screen will move, too. It'll also go between a birds-eye view and a backing-up perspective, and that can take some getting used to.

What was less convincing in terms of the user experience was the rear auto braking, which seemed to be scared of the car's own shadow. On multiple occasions the car jammed on the brakes when reversing out of driveways on to empty streets - be it in the normal height, or the raised height setting.

The 6 Series GT has dual ISOFIX anchor points and three top-tether points are there and ready for baby seats or child seats.

The A8 is covered by Audi Australia’s five-year/unlimited km warranty, which is now par for the luxury market course, and 24-hour roadside assistance is included for the duration.

Paint defects are also covered for five years, with rust (to the point of perforation) covered for 12. Nice.

Service is required every 12 months or 15,000km with a five-year capped-price plan for the A8 coming in at $3830, or $766 per year. That’s a fair wedge but not outrageous for the category.

BMW runs a condition-based servicing plan, which means the car will tell you when it needs servicing. But you can rest assured it won't (theoretically) cost you much, with the brand's 'Service Inclusive' pack. It covers you for basic maintenance as and when required for five years/80,000km. According to BMW, that includes "annual vehicle checks, oil changes, all filters, spark plugs and labour costs for the duration of the package".

BMW offers a three-year/unlimited kilometre warranty plan, and you get the same cover for roadside assistance.