Audi A8 vs BMW X4

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.

Okay, so the BMW X4 xDrive30i is neither an ass nor an elbow, to be fair, it's more of a bulky shoulder muscle, or two.

I can't say I'll ever love the X4, the idea of it is a bit too weird for me, but I can't help admiring the way it looks and the way it drives.

It's a bit like a sedan on steroids - or an SUV on a diet, depending on your perspective - but that doesn’t take away from the fact that it’s fun to drive, comfortable and retains just enough coolness, and just enough practicality, to make it worthwhile.

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?

So here's the thing. Obviously I have a personal beef with the existence of vehicles like this, but my eyes cannot deny the facts - the X4 looks fantastic. It's muscular, imposing and smooth all at once. Unlike the X6, a bigger and less visually successful attempt to play the same styling tricks with an X5, it doesn't have a ridiculous rear view that looks like it shoulders and buttocks have been fused (although it's hard to miss just how small the rear window is).

Even more impressively, there's no denying it looks better than the X3 that gave birth to it, so I can easily see why someone in a BMW showroom could be drawn to it. At least until they sit inside.

If the exterior style and eye-catching Sophisto Grey metallic paint don’t make an immediate impression then your eyes will surely widen at the interior, resplendent with bold Tacora Red seats, Aluminium Rhombicle trim finisher and the kind of sleek, classy styling that BMW excels in. 

Both the adjustable ambient lighting on the doors (we were partial to lilac) and door projectors that shot out what looked like robot wings onto the ground every time we hopped out of the X4 at night walked a fine line between futuristic cool and “parked out the front of a nightclub entrance” chintz, but over time the scales tipped more to the former. 

The big differentiator between the X4 and X3, of course, is the sloped coupé roof, a design feature that may make the X4 look a little cooler, but at the expense of cabin space, but more of that in a moment.

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.

For a car that is very much a mid-sized SUV on the outside, the interior can feel a bit too snug, like you’re driving a compact car that’s tried on a suit a few sizes too big (for reference, I’m 175cm tall - above-average height drivers may find the snugness soon turns to claustrophobia). 

While comfortable - it is BMW we’re talking about, after all - there’s not an overly abundant amount of headroom available, a feeling that becomes more pronounced should you shut the big moon roof.

My two children felt slightly too close to “you’re annoying me” distance from one another, which is to say this isn’t really the kind of car you should be getting if you plan on regularly ferrying about passengers in the rear who are bigger than a child. But I really don't think many people with kids would choose the X4 over the X3.

Boot space also takes a hit when compared to the X3 (550 litres versus 525-litres in the X4 - I was surprised the difference wasn't larger - although that expands to 1430-litres with the rear seats folded down. 

The boot opening is also mouth-shaped, which makes packing in wide-load items more of an issue.

Cupholders are plentiful - two in the front, two in the rear, and bottle holders in each door - and there’s a decent-sized storage cubby in between the front two seats. 

The sloped roof, and big fat A pillars, also result in the X4 being a bit more pinched at the rear, which is not especially great for visibility, with the vehicle’s blind spots taking some getting used to.

Cost-wise, the X4 is roughly in the same ballpark as the other cars in this strange sub-segment, but when you add in optional extras - metallic paint, panorama glass sunroof and BMW Laserlight headlights among them - the base price of $95,900 plus on-road costs sneaks up to $101,800, which is is no small figure. 

It’s also a considerable $8000 more than the SUV-shaped X3, meaning you’re essentially getting the same car, but with less cabin and boot space, for more money. To be fair, this is just part of a long tradition of the style-conscious buyer being willing to pay more for less, one that the invention of the coupe pretty much invented.

That kind of money also makes exclusions like adaptive cruise control, heated seats and wireless charging a bit of a head-scratcher.

Still, there’s plenty to love, including an M Sport kit that comes standard with the X4 (a suspension/brake package and various styling embellishments), butter-soft Tacora Red Vernasca leather seats (Sport adjustable for the driver and front passenger), 20-inch M light alloy double-spoked wheels, a head-up display, adaptive LED headlights, and an automatic tailgate. 

There’s also a generous high-resolution 12.3-inch control display and digital 12.3-inch instrument display, the former operated by touch or via the rotary iDrive Touch Controller. 

Cable-free Apple CarPlay and Android Auto are also available, but BMW allows you the option to use its iDrive system instead, just in case you're some kind of mad Munich fanboy - or you hate Apple. 

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. 

Now, prepare to be confused. In the past, the 3.0 in the xDrive3.0i nomenclature might have led you to believe you'd bought a BMW with a 3.0-litre straight six engine. But in this case, you have not, the 3.0 just means you have a more exciting version of the 2.0; a TwinPower turbo 2.0-litre inline four-cylinder engine, making 179kW and 353Nm that the xDrive system delivers to all four wheels. 

The claimed zero to 100km/h time of 4.9 seconds feels completely realistic as this engine has plenty of poke. Put it in the Sport setting and you'll get some serious shove. Indeed, the switch between Comfort and Sport is very noticeable and changes the character of the car entirely.

The transmission is an eight-speed conventional torque converter automatic gearbox that’s both smooth and responsive. 

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.

The X4’s 65-litre tank needs to be 95-octane at a minimum, and BMW’s claimed combined fuel consumption is 7.9 litres per 100km. The temptation to use its rorty little engine is going to push you higher, though - you chose the one with the 3.0 badge on it after all - and we averaged 10.9 litres per 100km in our week together, which was mainly city driving, to be fair. 

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.

The impressive trick that BMW continually pulls off with its SUVs is giving them the same sensual, muscular steering as its sedans, and an impressively similar ride and handling balance.

The steering is the highlight here, but it's also noticeable how planted to the road it feels.

The X4 speaks to its looks, in fact, by feeling sportier and more alive to drive than you'd expect an X3 to be.  

This is less an SUV for soccer mums and dads, and more a bastard love-child that’s into loud leather and bright neon - a CEO who dressed punk rock-lite on weekends, if you will. 

If those weekends are bereft of child taxiing and loading up the boot with several tons of kid stuff, then you’ll have a blast in the X4. 

A 2018 test gave the X4 a five-star ANCAP safety rating, and an easily located button on the dash brings up the vehicle’s safety suite if you’re the kind of driver who likes to make a few adjustments. 

A 360-degree camera offers multiple viewpoints and is a godsend when parking the X4, since the cabin makes the car feel smaller than it actually is on the outside, and the range of safety features on offer are more than adequate. 

Those include autonomous emergency braking, dynamic braking lights, dynamic stability and traction control, rear-cross traffic alert, speed limit information and hill descent control. 

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.

Despite all the brouhaha about other car manufacturers offering more generous warranty periods - seven years for Kia, for example - BMW has not shifted its stance, still offering its standard three-year unlimited-kilometre warranty. Frankly, it's just not good enough.

BMW also offer a Service Inclusive package for $2010 that covers owners for five years, or 80,000km.