BMW 6 Series vs Audi S4

What's the difference?

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 S4 and S5 range continues to represent a great formula for performance you can live with every day. They're arguably the sweetest balance Audi produces, actually. All come fantastically equipped, with cabins that feel truly special, and we’re lucky they can be had in a choice of five bodystyles.  

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.

The S4 sedan and Avant have scored the bulk of design updates, with all new and recontoured side panels including the sedan’s C-pillar matching what was applied to the A4 earlier this year. 

This is paired with new front and rear facias and lighting for a subtle but extensive rework of the fifth-generation S4’s conservative look. 

The S5 Sportback, Coupe and Cabriolet get S5-specific new lighting and facias, but no sheetmetal changes. As before, the Coupe and Cabriolet ride on a 60mm shorter wheelbase than the Sportback, sedan and Avant.

The S5s also get Matrix LED headlights as standard which do a neat animated sequence when you unlock the car. 

Other visual hallmarks include new S4-specific 19-inch wheels, with S5 stepping up to its own unique 20-inch wheel. The six-piston front brake calipers are appropriately painted red, and there’s S-specific adaptive dampers under there too. All variants aside from the Cabriolet get a lip spoiler on the rear.

On the inside, there’s a new centre console and bigger 10.1-inch multimedia screen, while the Audi Virtual Cockpit driver instrument display now offers a hockey stick-style rev counter in additional to traditional dial layouts.

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 biggest practicality change among the five S4 and S5 variants is their upgrade to the latest version of Audi’s MMI multimedia system, which steps up to a 10.1-inch touchscreen and drops the scroll wheel from the centre console.

It also boasts ten times the computing power of the version it replaces and uses this and an on-board sim card to access Google Earth maps for navigation and Audi Connect Plus that offers driver information such as fuel prices and parking information as well as point of interest search and weather information, plus the ability to make emergency calls and seek roadside assistance.

There’s also a wireless phone charger, but using Apple CarPlay will still require a cord as per Android Auto.

I only drove the S4 Avant and S5 Sportback at their media launch, which are clearly the most practical of the five, but from our experience with the previous versions, each looks after its occupants well in terms of space and storage. Back seat accommodation is clearly not a priority in the Coupe and Cabriolet, but there’s three other variants if that’s what you’re looking for. 

The Cabriolet can open its automatic folding soft top within 15 seconds, at speeds of up to 50 km/h.

As I mentioned above, the S4 and S5 line-up are in many ways the same, but also different, and these differences result in a price span of $20,500 between the S4 sedan and the S5 Cabriolet. 

The former is now $400 cheaper with a list price of $99,500, with the also-$400 cheaper S4 Avant not far beyond at $102,000.

The S5 Sportback and Coupe are now $600 more expensive at an equal list price of $106,500, while the swish folding soft top of the S5 Cabriolet pushes it up to $120,000 (+$1060).

Equipment levels are consistent across all five variants aside from the S5s getting Matrix LED headlights as standard and one inch larger 20-inch wheels. 

Key details include Nappa leather trim with front sport seats with seat heaters and massage function, a Bang & Olufsen sound system which spreads 755W across a total of 19 speakers, brushed aluminium inlays, head-up display, coloured ambient lighting, tinted windows and metallic paint.

Over the past 12 months, the S5 Sportback has proven to be the most popular of the five variants by far, accounting for 53 per cent of sales, with the S4 Avant next in line at 20 per cent, the S4 sedan making up 10 per cent, and the S5 Coupe and Cabriolet combining to make up the remaining 17 per cent.

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 has taken an ‘if it ain’t broke’ approach with the mechanicals, with all S4 and S5 models unchanged with this update. So the centrepiece continues to be the single-turbocharged 3.0-litre V6 that produces 260kW and 500Nm, with the latter available from a broad 1370-4500rpm.

The rest of the drivetrain is also unchanged, with the venerable but excellent ZF eight-speed torque converter auto paired with the Quattro all-wheel drive system that can send up to 85 per cent of drive to the rear wheels. 

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.

Official combined fuel figures range from 8.6L1/00km for the S4 sedan to 8.8L/100km for the Avant, Coupe and Sportback, while the heavier Cabriolet steps up to 9.1L/100km. 

All are pretty good considering their performance potential and the size of these cars, plus the fact that they only require 95 RON Premium Unleaded fuel.

All have a 58-litre fuel tank, which should enable a range of at least 637km between fills based on the Cabriolet’s figure.

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 S4 and S5 range were already an excellent balance between everyday comfort and a genuine sporting edge, and nothing has changed with this update.

I spent time behind the wheel of the S4 Avant and S5 Sportback at their media launch, and both managed to deliver the proper Audi luxury experience over some pretty rough rural roads, while always feeling a bit more sporting than a regular A4 or A5. That’s with the Drive Select left in the default mode, but you can shift that sporting personality up a few notches (while scaling back the comfort), by selecting Dynamic mode. 

My preferred means of adjusting their personality is by simply tugging the transmission selector back to activate S mode, which livens up the engine and transmission without stiffening up the suspension. 

Across the five S4 and S5 bodystyles, there is some variance in performance potential, with the S4 sedan and S5 Coupe topping the performance chart with 0-100km/h boasts of 4.7s, with the S5 Sportback trailing them by 0.1s, the S4 Avant by a further 0.1s and the Cabriolet managing a still-fast 5.1s claim.

Another area I consider the S4 and S5s to get just right is their exhaust note. It is adaptive, but there’s nothing synthetic about it, and the generally muted and distinctly V6 burble is always there to remind you that you’re aboard a proper performance model, but not in such a way that it will annoy you, or your neighbours. Polite performance, if you will.

All S4 and S5 variants boast an impressive array of safety features, but there’s some interesting points when it comes to ANCAP ratings. Only four cylinder A4 models (therefore not S4) were given a maximum five star rating when tested according to less stringent 2015 standards, but all A5 variants (therefore S5) aside from the Cabriolet carry a five star rating based on the tests applied to the A4. So officially, the S4 is not rated, but the S5 Coupe and Sportback are, but based on the A4 rating that doesn’t apply to the S4. As with most convertibles, the Cabriolet is simply not rated. 

The airbag count totals eight in the sedan, Avant and Sportback, with dual front airbags, plus side and curtain airbags covering front and rear.

The Coupe drops the rear side airbags, while the Cabriolet also drops curtain airbags, meaning there’s no airbags for rear seat occupants. The roof is made of folding fabric, there has to be some safety compromise.

Other safety features include front AEB that works up to 85km/h, adaptive cruise control with traffic jam assist, active lane guidance and collision avoidance assist that can automatically swerve, a 360 degree camera system, rear cross-traffic alerts, exit warning that can prevent you opening a door into an oncoming car or cyclist, and pre sense rear that can detect an impending collision from behind and prepare the seatbelts and windows for maximum protection.

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.

Audi continues to offer a three year, unlimited kilometre warranty, which is in line with BMW but lags behind the five years offered by Mercedes-Benz these days. This also contrasts with the five year norm among mainstream brands, which is punctuated by the seven year warranties of Kia and SsangYong.  

Service intervals are a convenient 12 months/15,000km though, and the same five year ‘Audi Genuine Care Service Plan’ offers capped price servicing for the same $2950 total over five years applies to all S4 and S5 variants. This is only marginally more than the plans offered for regular petrol A4 and A5 variants, so you’re not being stung for the thoroughbred versions.