2018 BMW 630I vs 2024 Audi RS6

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.

To me at least, the RS6 is pretty much the ultimate fast and practical car. One which is just as comfortable plodding around town as it is tearing it up on the track. Keep in mind, too, this may be one of your last chances to have a car which looks like this, equipped with a V8 engine. So, have I convinced you? Would you consider one of these over a performance SUV? Tell us what you think in the comments below.

Note: CarsGuide attended this event as a guest of the manufacturer, with travel, accommodation and meals provided.

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.

At a distance the RS6 is just an unassuming station wagon, but the closer you get, the more apparent it becomes how mean it is. It’s wide, it’s chiselled, it’s not just good looking, it’s iconically Audi.

The stance is so wide, its ride height so low, and its wheels are so massive that any keen eye will be able to spot where the difference is between this and any old family hauler.

Wagons may not be trendy, but there’s something undeniably cool about having the hauling capacity of an SUV at the ride height of a sedan.

Of course, if you want to look even more svelte and don’t need the boot space, the RS7 is always lurking around at a slight price premium.

Inside, the RS6 has all the modern amenities of the Audi range. Expect the usual sharp screens, lovely sports seats, and a tasteful application of textures throughout.

There’s a blend of carbon-look finishes, chrome, leather and gloss black. Perhaps a little too much gloss black to keep clean, but the aesthetic is suitably upmarket. 

You can go to town on customisation, and the car we primarily tested had stitching and colour in the carbon patterns to match its 'Ascari Blue' exterior, but you can pick whatever shade or combination of colours your budget allows.

Audi’s software is pretty good these days, with an attractive theme and fast hardware to back it, and the brand’s ‘Virtual Cockpit’ is still one of the most aesthetically pleasing and customisable digital instrument systems on the market, despite being one of the first.

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.

Okay, I promised a car with the practicality of an equivalent SUV, but it’s not quite there. The trade-off is still worth it, I promise, but there are a few areas where the RS6 isn’t as practical as you think it’s going to be, particularly for front occupants.

Yes, it’s a big wide car, with large but supportive seats and plenty of headroom, but the issue for those travelling in the front two seats is the surprisingly limited amount of storage.

Yes, there are two bottle holders in the centre console with a folding tray lid to hide them away, but they aren’t huge. Bigger bottles would have to go in the door bins, but even then they’re a bit height-constrained.

There’s a decent glove box on the passenger side, but even the centre console box is very shallow, with more than half of it taken up by a wireless phone charger.

The touch panel for the climate unit looks impressive but still can’t match having physical dials. It has clicky haptic feedback to your individual presses, and all the functions are permanently accessible instead of hidden in sub-menus, so if you’re going to make climate a touch-based interface, it doesn’t get much better than this.

Where the RS6 shines is in the back seat. Despite those big bucket front seats, I had heaps of room behind my own seating position (at 182cm tall), with lots of headroom and sufficient width in the cabin to spread out.

You sink into the rear seats, which are heavily contoured so riding in the back is a pretty good experience even on the track.

Rear passengers get four adjustable air vents in both the B pillars and in the centre, as well as their own touch panel for the rear climate zone.

USB power outlets are also available, and there are netted pockets on the front of both back seats, with a further two bottle holders in the drop-down armrest.

The centre seat is probably only good for kids, because there’s a very tall raise in the centre required for the driveshaft, eating all the legroom.

The boot is fairly large at 548 litres which is in mid-size SUV territory, although I will admit some performance SUV rivals offer closer to 600L.

Space expands to 1658L with the second row folded flat.

Let’s start with the bad news. Most people can’t afford one of these. The RS6, in all of its muscular glory, is more expensive than ever before. Now wearing a before-on-roads price-tag of $241,500, it’s hardly your average mum and dad family hauler. But then, there’s nothing average about the RS6.

It’s so well regarded amongst enthusiasts for multiple reasons. It’s the biggest meanest wagon you can buy, and somehow Audi has managed to make this version more powerful and even faster than before.

In fact, it’s one of the few normal looking combustion cars out there which can still hold a candle to many electric cars, with its whomping V8 helping it warp from 0 to 100km/h in just 3.4 seconds.

More on those performance specs later. If you’re wondering what else you get for your near-quarter-of-a-mill it’s pretty much every spec item Audi currently offers.

There are now lighter 22-inch alloy wheels, adaptive air suspension, a high-performance braking system, an RS-specific exhaust system, matrix LED headlights with adaptive high beams, a 10.1-inch multimedia touchscreen with navigation and wireless phone mirroring and one of the best digital instrument clusters on the market.

It also features Valcona leather interior trim, sporty bucket seats with perforated trim, honeycomb stitching, as well as ventilation and heating, additional cabin trim in synthetic suede (comprised of 45 per cent recycled fibres), ambient interior lighting and a panoramic sunroof.

It’s a lot of stuff, but one thing you get a little less of is sound insulation. Audi has chosen to remove some of it this time around so you can hear the V8 better from behind the wheel.

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.

The RS6 is still packing eight cylinders in 2023, producing a massive 463kW/850Nm, somehow an increase (+22kW/50Nm) over the previous iteration.

Audi’s signature ‘Quattro’ all-wheel drive system is present alongside a limited-slip differential and four-wheel steering.

Air suspension and performance brakes and exhaust also feature, alongside an aggressive Continental SportContact 7 tyre package.

The 0-100km/h sprint time is now just 3.4 seconds, allowing you to show up even some electric cars, and the RS6 features 48-volt mild hybrid technology with a cylinder-on-demand system which can shut half the block down for more efficient coasting.

The transmission is an eight-speed torque converter unit which is smooth and effortless.

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.

Officially, the RS6 and its eight cylinders drink a combined 11.8L/100km, although even with its fancy hybrid system and cylinder deactivation, my time with the car saw 15.0L/100km. The RS6 has a 72-litre fuel tank and takes only the finest 98RON unleaded fuel.

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.

As you might have guessed from its impressive engine and performance equipment, the RS6 is a certified weapon on road and track.

On the road you can expect a quiet, refined cabin, superbly balanced steering for low and high speeds and a gentle ride quality courtesy of the pricey air set-up.

It’s as noisy or as quiet as you want it to be, with the cylinder deactivation toning things down at low speeds, and the engine roaring to life under heavy acceleration, or when the 'Dynamic' drive mode is selected.

It can at times be alarming how much the RS6 leaps to life, as it feels so cushy in a city, its width and cabin giving the feel of a luxury car rather than a performance one.

Make no mistake, though, the RS6 is properly quick, and when you give it a kick, it’s the roaring, aggressive machine the spec sheet suggests.

The best place for this? The track, of course. The big V8 and the capability of the all-wheel drive system are truly best explored at velocities impossible to legally achieve on the road.

Once you get past the bark and snarl of this wagon’s eight-cylinders at full force, and the lightning-fast shifts of its eight-speed automatic, you’ll have a moment to appreciate the way it simply holds to the tarmac when you tilt it into the corners, providing a balance when loaded up which only air suspension can provide.

The steering is awesome, communicating the texture of the road nicely to the driver, and requiring just the right amount of force to keep the car pointing where it needs to go.

The grip level is astounding with the huge tyres and the four-wheel steer system lets this hefty wagon take corners at a tighter angle than your brain initially allows.

Thankfully, the four-wheel steer system isn’t weird, either. While it can have a strange effect on some cars, in the RS6 it only bends your mind slightly when you tip it into a hairpin. Otherwise it feels pretty normal.

When everything is warmed up, it can let its guard down slightly and allows the driver to eke out a slide at the rear here and there for extra fun-factor

Jeez. What a machine. I guess this is what a quarter of a million dollars buys. A car that can do it all. Take the kids to the school in comfort and tear it up on the track like few other passenger cars on the same day.

There’s a caveat, though. A small one which looks like it will turn into a big one for cars like this in the near future.

I had the opportunity to drive the RS e-tron GT around the same circuit and it was better. Much better.

It was faster, more accurate, more composed. It was so effortless, I didn’t realise exactly how much quicker than the RS6 it was until I drove them back-to-back.

It’s a good sign for the future, but also a reminder a V8 like this isn’t the performance pinnacle it once was.

Like its standard cabin equipment, the RS6 has had the entire catalogue thrown at it for active safety gear. Included is freeway-speed auto emergency braking with pedestrian, cyclist, and intersection detection, lane keep assist with lane departure warning, blind-spot monitoring with rear cross-traffic alert, an exit warning system, and adaptve cruise control with traffic jam assist.

Elsewhere the RS6 gets dual front, dual side, and head curtain airbags, with ISOFIX points on the outer two rear seats as well as three top-tethers across the rear row.

The RS6 is not safety rated by ANCAP, but the rest of the A6 range was awarded a maximum five stars in 2018. 

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.

Five years and unlimited kilometres is the warranty length, and Audi’s ownership program includes invites to events like the one we were able to experience for the launch of this car. A track-test of the RS6 and the RS e-tron GT.

If you own one, I recommend them, you’ll learn a thing or two about the car and possibly yourself while you’re at it.

Servicing is required once every 12 months or 15,000km, and a service pack covering the first five years or 75,000km can be purchased alongside the car at a cost of $4360.

It works out at $872 per year, which isn't economy car cheap, but with such a complex drivetrain, what did you expect?