BMW 840I vs BMW M4

What's the difference?

If you’re the sort of buyer who wants a car that signifies a lifestyle that is ‘large and in charge’, the BMW M850i Gran Coupe could be just the thing for you. It isn’t as showy as some of its competitors, and mightn’t reach the same levels of excitement as those cars either - but it is a convincing offering in its own right, and a beautiful piece of design at that. 

Brutal, bruising and utterly brilliant, the M4 CS will be an acquired taste due to its no-compromise approach, but those willing to take the leap will find a performance car like few others at their disposal.

This could be BMW’s most convincing design in years. I mean, the X5 is predictably handsome, the X3 was unexpectedly muscled, and the less said about the frumpy 1 Series and busy 3 Series (apart from the wagon… drool) the better.

To my untrained but enthusiastic eye, the 8 Series Coupe is a bit too rounded over its rear haunches, and the rear screen is just a little steep - to me, that lets its dimensions down a little. But this. This is gorgeous. 

I mean, you might have questions over the tail-light design, which is a theme across a few BMW models now. But there isn’t as much confrontation between horizontal and vertical graphics for this model as you’ll find one other big Bimmers, like the X7. 

The M850i model has BMW Laserlight headlights, which throw a sharp beam and look menacing in their signature, while the grille and bumper are strong. The stance of the car is prominent - there’s a long body, a long wheelbase, and a long body in general. The standard wheel package consists of 20-inch rims, and they don’t look disarmingly large.

As our images show, there’s a lot to talk about when it comes interior design and finishes, but the cabin doesn’t quite benefit quite as mochas you might think it would from all that real estate. I mean, with dimensions of 5074mm long (on a 3023mm wheelbase), 1932mm wide and 1402mm tall, this is a squat, yet substantial vehicle. It’s just more cramped than you’d think inside.

The M4 CS is familiar in all the right ways, but definitely looks significantly jacked up compared to its lesser siblings.

Part of that is the extensive use of carbon everywhere, from its bonnet panels to its roof, front lip, side skirting and boot spoiler. But also because of its super-muscular angles and creases, including the huge dome in its bonnet.

Also exclusive to this M4 CS is the light treatment, with the front LEDs lighting up with yellow highlights the brand says are supposed to be reminiscent of GT racing cars.

At the back, the rear lights are flush with fibre optic lighting, lending a flowing and unique light signature that looks epic at night.

Inside, it's a sea of carbon, with the lightweight racing seats, the dash inserts and the centre console all lined in it. It is a perfectly finished space, though, and one that's also flecked with red, including a 12 o'clock band on the thick-rimmed steering wheel, the seat backs, the contrast stitching and the paddle shifts.

Be warned, though, it takes some acrobatics to climb into or out of the CS. The seat bottoms have these super high edges that double as grab handles, but require some awkward contortions to navigate.

In short, it looks angry, this M4 CS, inside and out.

I recall a Mitsubishi designer telling me, once upon a time, that he dreamed of making ‘a big car on the outside with a very small interior’. Maybe he made the jump to BMW, because that’s pretty much the 8 Series Gran Coupe.

There aren’t many other vehicles on the market, of this size, that offer less space inside. The boot capacity, for instance, is just 440 litres. Competitors like the Audi A7 (535L) and Mercedes CLS (520L) easily outdo it - but at least this car has more boot than the Panamera (405L), though the BMW is a smidge bigger. The cargo space is large enough for a couple of overnight suitcases, but you’re hardly going to fit a family of four’s luggage for a week away. 

And while we’re in the “not quite what you’d expect” column, the back seat space is hardly commodious. There’s enough space for me, at 182cm, to sit behind my own driving position, but not without wishing for a bit more toeroom, headroom and knee space. 

The big centre console section eats into the space in the rear, justifying the brand’s “4+1” seating claim, and unpleasantly it has a hard plastic finish to rest your leg against. Getting in and out of the second row isn’t easy for bigger people, and it’s quite a squat down into the rear seat - it really has taken inspiration from its squashy-back-seated predecessor in that regard.

If you have smaller rear-seat occupants, however, there will be catered for with dual ISOFIX and three top-tether points, plus there are air vents with climate controls (quad zone in total), and two USB-C ports as well. There are sun-blinds on the rear windows, too, which is a plus, and there is a pair of cup holders in the fold-down armrest, and map pockets in the seat backs, too. The door pockets are near-useless, though.

The front seats score better practicality, with bottle holders in the doors, bigger and sturdier cup holders, a covered centre storage bin between the seats with a USB-C port, and a wireless phone charger (Qi) with standard USB port in front of the gear selector.

Above that is the weird, very out-of-place quick buttons (1-8) that BMW could easily do away with, and further up are the controls for the climate control (thankfully with hard buttons for fan speed and temperature), and above that is the media screen, a familiar looking 10.25-inch touch display running BMW OS 7.0. 

The screen is quick and crisp, and is backed up by the rotary controller and buttons on in the centre console area. There’s wireless Apple CarPlay (now at no cost for three years), as well as a built-in SIM card for 4G data and access to the BMW Online news and weather stations, accessed through the screen.  

It’s all pretty easy to use, and the sound system is excellent - the standard setup consists of 16 speakers, with DAB+ digital radio, Bluetooth and USB plus the smartphone mirroring tech, provided you don’t have an Android device, as Android Auto is still missing from BMW’s range.

It’s a nice cabin, but I couldn’t help but thinking that I’d want a little more differentiation from the lesser models in the range if I was spending this much. Especially considering the optional cost of the interior trim fitted to our test car - see below for more detail.

It all boils down to how you classify practicality in a car like this. I mean, the basic stuff is all there – it's got two doors, four seats and a boot capacity of 440 litres.

It measures 4801mm in length, 1918mm in width and 1399mm in height, and room for front seat riders is good, but less so for anyone you squeeze into the back. There are even ISOFIX points for a child seat.

But if you consider practicality the practical pursuit of performance, then the M4 CS has plenty of perks.

We're talking a $254,900 entry price for the M4 CS, which – despite my attempts at justification – is a lot. Remember, the regular M4 is $168,700, and the M4 Competition is $186,500, so we're talking a sizeable premium here.

BMW justifies that price increase in two ways. The first is scarcity, with the M4 CS limited to just 50 examples in Australia. And the second is by dialling up every aspect of the M4's performance to terrifying levels.

The engine outputs are up, the weight is 20kg down, there are better brakes, better seats, a louder exhaust, a stiffer chassis – it goes on and on.

We'll get to some of the performance stuff in a moment, but here's what else your money buys you with the M4 CS.

It starts outside with staggered alloys, 19-inch up front and 20-inch at the rear, wrapped in track-ready rubber. There's also hi-po 'M Compound' brakes with red calipers, lightweight carbon racing seats that are heated up front, an Alcantara-trimmed steering wheel, the 'M Carbon' exterior package with carbon bonnet and roof, adaptive 'M Suspension' and a titanium exhaust that howls like the winds of hell.

The less performance-focused stuff is similar enough to the other M4 models including a 12.3-inch centre screen with digital radio, Apple CarPlay and Android Auto, a second 14.9-inch screen that handles your driving data and a head-up display. There's also twin-zone climate control, Merino leather upholstery and ambient interior lighting.

But all of that is secondary, really. This is about performance, specifically of the brutal kind.

If you’re going for the M850i, you’re getting the big bopper engine. It’s a 4.4-litre twin-turbo V8 petrol engine, and it isn’t short on horsepower.

The outputs for this engine are 390kW of power (at 6000rpm) and 750Nm of torque (from 1800-4600rpm). Hardly numbers to sneeze at.

And the performance figures are exceptional, too: the claimed 0-100 km/h time is just 3.9 seconds. That’s because there’s the traction of BMW’s xDrive all-wheel drive system, and shifting gears is an eight-speed automatic transmission.  

For what it’s worth, your humble reviewer saw a 0-100km/h time very close to that (4.2sec). 

The quoted kerb weight for this model is 1995kg.

BMW has found yet more grunt lurking in its trusty 3.0-litre 'M TwinPower' six-cylinder petrol engine, with the M4 CS now pumping out 405kW and 650Nm.

That's a decent jump from the 390kW and 620Nm served up by the M4 Competition, and a giant leap from the outputs of the 'base' M4 – 353kW and 550Nm.

Predictably, then, the CS is the fastest of the lot, knocking off the run from 0-100km/h in 3.4 seconds, compared to 3.5 and 4.2 in the Competition and M4, respectively. The top speed is also dialled up to 302km/h.

All that power is channeled through an eight-speed automatic and sent to all four wheels on demand, with the help of an 'Active M Differential'.

You can’t really expect a big V8 beast like this to be a fuel miser, and it isn’t.

The claimed consumption is 10.7 litres per 100 kilometres. Which is alright, honestly, given the sheer volume of car you’re driving. 

But on my test - which consisted of more than 300km of mixed driving, including days of city commuting, some twisty mountain driving, and all the freeway floundering to get there - I saw an at the pump real-world figure of 15.4L/100km.

That’s not very efficient, and it’ll be expensive to run on the daily — yet the argument could be made that if you’re spending this much on a car, fuel costs won’t matter much to you. But with a small fuel tank capacity of 68 litres, it could become a little inconvenient as you’ll be seeing a lot of your local servo.

The M4 CS is fitted with a 59-litre fuel tank, which – given the BMW's official fuel claim of 10.2 litres per hundred kilometres – should deliver a driving range on a full tank of 541 kilometres.

But... BMW also says the regular M4 – you know, the one that makes 52 fewer kilowatts and 55Nm less torque – uses 10.1L/100km, so do with that information what you will.

It’s an impressive thing, this M850i xDrive Gran Coupe. But I’m just not sure who it’s trying to please.

It’s not the sort of German monster coupe-sedan that grabs you by the scruff of the neck and throws you around with its mammoth acceleration. Not unless you poke it and prod it and make it really angry.

And that might be exactly what you want to do - put it in Sport mode, sling the shifter across to sport or manual mode, hear the exhaust open up from a pursed-lip tongue-click to an open-mouth growl. 

You’ll push hard on the accelerator, watch the tacho needle jolt to the redline, and if you’re in auto mode you’ll feel the transmission whipcrack as it shifts rapidly up through the gears as you’re shoved back into your seat. Before you know it you’ll be in licence-loss zone, and you won’t have even made the tyres chirp - that’s how immense the traction from the all-wheel drive system is.

You’ll brake hard into a sharp bend, and you’ll feel the front end dip and the body of the car change direction more readily than you’d think given its size as you turn in. The steering response will meet your expectation, with rapid reaction to adjustments mid corner. And the Active Roll stabilisation system will mean you’re not being thrown around in your seat, because it’s sitting flatter and truer than you might have expected - you’ll notice how it works extremely well in conjunction with the car’s torque-vectoring-by-braking system. There’ll be little weight shift or body roll to be counteracted, and that’ll inspire you to push it even harder.

Put it in manual transmission mode and you’ll rejoice that it won’t overrule you and shift up, but you’ll also feel shortchanged because it gets to the end of its limit very quickly. And when it hits redline, it emits a breathless little cough rather than a “oh maybe I should stop” rev-bounce noise.

But, if you’re like me, you might be doing all this with a niggling thought in the back of your mind that, while this car is technically really good and it’s a clinical performance car, you might just think to yourself, “I’m not having as much fun as I thought I would”.

A Mercedes-AMG would be more fun; it’d be more raucous, more of a muscle car experience. An Audi RS7 (at least the previous one) would be noisier, brasher, more theatrical than this car. And likewise, a Porsche Panamera - no matter the model you go for - would be more entertaining in the bends.  

Maybe it’s just a bit too predictable - and maybe that’s a result of this car being honed for drivers who will spend more time on the Autobahn than anywhere else. I have to say, there are much, much worse (and slower) ways of getting from A to B, and the highway cruising comfort of the M850i Gran Coupe was what impressed me most. 

It’s also surprisingly adept at urban driving duties, coping well with unpleasant city surfaces, though potholes can still upset things because of the stiff-sidewalled run-flat tyres. The suspension does an exceptional job otherwise, however, and I switched between the Adaptive drive mode and Comfort mode for my commuting duties. Both proved comfortable and controlled.

The M850i is by no means a failure when it comes to fulfilling the expectations you might have of a luxury sports sedan of this size. In fact, it’s close to a distinction. But I just can’t help thinking that it’s not as much an ‘M car’ as that M850i badge might have you believe it should be.

The hardest and angriest M4 of all time is, perhaps unsurprisingly, hard and angry. This is a race track specialist, but because I don't happen to own one of those, my first experience with the barking (and barking mad) M4 CS was navigating my way back from BMW's inner-city dealership.

Like it or lump it, you're going to read some Porsche comparisons here, because you're talking not too far off base 911 Carrera money, and suddenly I find the two Germans doing battle for a spot in my dream garage.

First things first, the BMW won't be much chop for daily driving for most people. Happily, I have a sickness for uncomfortable sports cars. It tells me that no compromises have been made in the pursuit of punishing performance.

A good thing, too, because the BMW, at city speeds, can be punishing. Everything feels heavy, the seats aren't overly comfortable – especially the hard bits that tend to dig in when cornering – and it stiff-arms its way over road imperfections, that exhaust booming and barking as it does.

Again, I loved it, and you probably will, too. But it's still not the kind of car I'd relish sitting in the morning peak hour rush in.

But escape the confines of the city and the BMW M4 CS suddenly makes a whole heap of sense. The acceleration is genuinely brutal, and wonderfully theatrical, with that quad-tipped titanium exhaust barking and snarling as you rocket towards 100km/h.

The steering is brilliant, with feedback fed to your wrists via that thick-rimmed wheel, and the entire experience feels sharp, super engaging and edgy.

You can push the M4 hard and fast, and I'm certain my limited talents would run out far before the BMW's would, but there's this thrilling sense of peril sparked by the aggression of the experience, that I love.

It's like the magic of a roller-coaster, I guess. Even if you know nothing is going to happen, you never really know, right? And in that lies the magic.

But back to original question, this or a Porsche 911? There's no doubt a Carrera is a better all-rounder, in terms of comfy commuting and race track fun, but this angry M4 is all shouty theatrics, all of the time.

I bloody love it.

Expect no ANCAP rating here, I'm afraid. But the BMW 4 Series does wear a five-star rating from 2019.

The M4 CS gets six airbags (driver and passenger, side airbags, head airbags), along with what BMW calls its 'Driving Assistant Professional', which bundles active cruise control (with stop and go function), front and rear cross-traffic warning, 'Steering & Lane Control' and 'Lane Keeping with Side Collision Warning'.

BMW backs its cars in Australia with a three-year/unlimited kilometre warranty.

You may be confused if you head to the BMW site and see that M models and 8 Series models aren’t covered by BMW’s pre-pay capped price servicing plan (as I saw when testing this car), but CarsGuide can confirm that the 8 Series is indeed covered - unless it’s the real M8, not this M850i jigger. 

BMW Australia has clarified that the Service Inclusive pack for five years/80,000km of maintenance cover is $2490 for Basic cover (no brakes/pads, no wiper replacement), or $5641 for the more comprehensive Plus pack. Hardly affordable, but nor’s the car. 

The company uses a condition-based servicing program, too - there are no set service intervals, but the car will tell you when it needs maintenance based on how you drive it.

For what it’s worth, we ran the numbers on resale value using Glass’s Guide predictive analysis tool, and after three years/40,000km the expected retained value for this version is approximately 66 per cent - which is impressive.

The M4 CS is covered by BMW's five-year, unlimited-kilometre warranty, with condition-based servicing available in packs, which will cost you $3530 over five years/80,000km, or $2900 over four years/60,000km.