BMW M3 vs Mercedes-AMG C63 vs Alfa Giulia Quadrifoglio vs Audi RS4 (2021) group test review

Published: 28 May 2021

► BMW’s M3 up against classic rivals
► It was a tie against a 911
► How does it fare with this lot?

So, BMW’s re-inventing itself. Before all that, though, is its new M3 the real deal? Last month it forced a draw from the Porsche 911. Now, the old rivals: Alfa, Audi, AMG. Fight!

Pre-flight briefing: BMW M3

What’s the CV?
Not the original M car, but M3 is the bullseye on the M division dartboard. We wouldn’t give the previous-gen a reference. New one top of the class.

If it were an Olympian it’d be…
Pole vault champion. Bit of a run up, then a big pointy arc of power delivery over a wobbly bar the others can’t clear.

m3 interior

The 10-second sales pitch
High-revving straight six, oversteer lunatic, family hack, tech showcase, probably the last rear-drive M3.

Don’t buy one if…
You’re a shrinking violet – like a dangerous dog on start-up and these looks aren’t shy, but reaction on our shoot says people like it.

Pre-flight briefing: Mercedes-AMG C63 S

What’s the CV?
The car that proved AMG could challenge M on dynamics as well as performance, while still going its own way. Two generations in, a legend.

If it were an Olympian it’d be…
Russian shot put ace. Monster muscle, spins up from a standing start, some suspicion over steroid abuse.

c63 interior

The 10-second sales pitch
The only V8 on test, a rumble like thunder, shot-through with precision dynamics. Next one’s a four- cylinder, so hurry hurry.

Don’t buy one if…
You don’t want to wake the neighbours but you do want the latest thing – C63 is rowdy, and it’s not long for this world.

Pre-flight briefing: Alfa Giulia Quadrifoglio

What’s the CV?
Cloverleaf badge goes back to Alfa’s racing roots, but Giulia is a clean-sheet new chapter that made the last M3 feel numb.

If it were an Olympian it’d be…
A shoo-in for a gymnastics medal – limber-limbed, flows delicately down a road, wobbles when the pressure’s on.

alfa interior

The 10-second sales pitch
Forget the Germans, get some Italian passion on your driveway. Drives with flair and excitement, and drop-dead gorgeous too.

Don’t buy one if…
You need space in the back or you want the last word in interior quality. Giulia is all about the looks and the drive.

Pre-flight briefing: Audi RS4

What’s the CV?
Now four generations old, and still living in the shadow of 2006’s B7 V8. All-wheel drive and estate bodies since before it was fashionable.

If it were an Olympian it’d be…
Straight to the Winter Olympics for a gold in Alpine Skiing.

rs4 interior

The 10-second sales pitch
Mini RS6, anti-M3 – a high-performance car that won’t try to kill you, doesn’t look embarrassing and has space for things.

Don’t buy one if…
You want to buzz with excitement after every drive, and you commute on bumpy roads. Handling neutral, ride so-so.

Back to business: driving the new M3

m3 drift

Some people think coriander tastes soapy. This is because their olfactory-receptor gene translates its herby taste into a Fairy Liquid tang. Perhaps a similar phenomenon occurred with the previous BMW M3. People I respect rated it, but I got a distinct taste of diesel truck with overtones of snap oversteer.

The new G80 M3 starts to heal the relationship below 20mph. I’m creeping away from home early to meet the others in the Peak District, and even now the M3 Competition feels rock-solid – it’s a structural rather than bone-shaking thing, kind of a if-McLaren-did-super-saloons sense of togetherness. One word? Tight.

Then there’s the seating position in gorgeous (optional) carbonfibre bucket seats – touring-car low, grip like riding a loop-the-loop rollercoaster – plus the steering is quick, pretty feelsome and light-ish, helping ease away a chunky 1730kg. I’m connected to this car like a plug in a socket.

Flying start, then, but we’re heading to the Peaks to give the Competition some lower-case competition with the Mercedes-AMG C63 S, Alfa Giulia Quadrifoglio and Audi RS4. Our route promises to provide a stern test. Up there you need grip if you’re to avoid having to ask Mountain Rescue for a recovery truck, strong performance to power up elevations like funicular railways, and brakes that laugh in the face of 30 per cent descents. Crucially, you need suspension that gels with the tricky primary undulations that define the dramatic landscape.

For now, the M3’s making a decent job of the drive there. Its suspension is resolutely focused (Comfort is all you need in the UK), but it retains daily usable compliance, and while the straight-six still impersonates a big diesel at a cruise, it’s super-smooth and just a flex of the toe hints at the almighty power to be tapped – 503bhp and 479lb ft, chunky increases of 59bhp and 74lb ft over its predecessor.

A lorry holding up a queue of cars moves aside, and with a quick squeeze, the couple of fast corners beyond see the M3 turn and settle in with one clean movement before hooking up and powering out. We’re shifting along with probably 50 per cent in reserve, yet there’s no sense of detachment – more anticipation of uncorking the rest.

m3 ben driving

Minor roads in the Peaks bring a chance to work the M3 harder along routes that are all long sweeps that rise and fall over epic mountainsides, the guard rails painted like chequered flags and dry-stone walls punched with car-shaped holes.

Georg Kacher found the M3’s steering a little nervous at 180mph last month when he compared it with the Porsche 911, but at a third of that lick the variable ratio is merely extremely responsive. It also reveals how well resolved this chassis is, because while it’s easy to chuck a fast rack in a car, it’s far harder for the chassis to keep pace. The M3’s does. The front tyres grip this gnarled surface like a nail’s been driven through the BMW badge into the apex (the 275-section Michelin Pilot Sport 4S tyres are significantly wider than any rival here) until eventually the rear tyres let go, if with so much lateral support that it’s more fluid arc than fark.

Same deal with traction. The M3 can still be a psychopath, but this time you feel it losing its temper more transparently while easing in the throttle. It’s more progressive as it goes, all of which makes balancing everything on a deliciously razor-sharp throttle more intuitive. When the rear tyres do fizz, there’s excitement in the straight-six too: peak power still floods in at 7200rpm, there’s more treble in the soundtrack, and still a furious rate of forward motion even with traction compromised.

The M xDrive model will no doubt be quicker, and we know how versatile the M5 is with its all-wheel-drive system, but this rear-drive M3 with the new 10-stage traction control system would make me think twice about adding the weight and cost of xDrive – it works so well.

Mercedes-AMG C63 S: ageing un-gracefully

When I meet the others, our car-park rendezvous is shrouded in fog and lashed with wind. While the others plot some changes to our proposed test route, I retreat to better conditions in the C63 S Coupe.

Though it remains smart, the Mercedes’ interior most obviously betrays its age, and a replacement C-Class has already been unveiled. Two things, though: the C63 S received some worthwhile updates in late 2018 to help keep it competitive, and its replacement will switch to an electrified four-cylinder and bin this car’s USP: a 4.0-litre twin-turbo V8 hand-built in Affalterbach and defined by a glorious rumble like God’s own furniture removers. Sod the interior, we should be panic-buying C63s like loo roll in a pandemic.

The figures reveal how the decades-old torque versus revs divide persists between AMG and M division – the AMG delivers its test-best 516lb ft peak some 1000rpm lower than the M3, and stops producing the same 503bhp peak 1000rpm sooner too (a base C63 is available used with less kit and power, unlike the M3). You sense that torque working the AMG’s rear tyres every time you feed in the throttle, and see red shift lights sooner because there’s not quite the furious reach of the M3’s powerband. But there’s incisive throttle response, barely perceptible lag from turbos that you can actually see nesting in the ‘hot vee’ of the V8 , and power and attitude ladled on everywhere. You couldn’t call the gearshifts exactly snappy (the updates brought a new nine-speed MCT auto), but they’re quick enough, and even M division’s torque converter doesn’t have the old dual-clutch punch.

c63 giulia downhill

Like the M3, the AMG quickly communicates its structural stiffness, as though you could stomp on its tail and pop it off the ground like a seven-ply maple skateboard. It rides with a more deeply cushioned pliancy, though, and has a meatier weight and enhanced feel through its more relaxed and arguably more natural-feeling fixed-ratio steering than the M3. The chassis also brims with bite and road-surface texture (and no shortage of road noise), encouraging you to carve it hard, and even when you pitch it into tighter corners at over-ambitious speeds, there’s just a little chirrup from the front Michelin Super Sports. Jake Groves highlights the brakes after his drive, holding a thumb and forefinger millimetres apart to illustrate how promptly the pedal engages. These pads are aggressive – get ’em hot and they squeak while you’re parking.

AMG Dynamic Select settings are familiar for tweaking parameters (from memory, Medical Car, Safety Car, Faster Valtteri, Lewis Plus?) and S spec allows you to adjust them via a dial on the steering wheel rather than fumble with buttons you can’t properly see on the centre console. But the late-2018 update also brought settings to tweak the electronically controlled limited-slip diff and new nine-stage traction control just like the AMG GT-R. The latter is clever but pretty straightforward: wind it off to build up to your crash.

I head out to experiment on a dry road lower down the mountainside, remembering just how effortlessly oversteery the pre-facelift C63 was, and eventually dial it to zero. Even with provocation, the C63 feels rear-biased but reluctant to budge. I’m bewildered and end up on my knees in the car park checking for front driveshafts. Then I realise the AMG Dynamics diff tuning is in Advanced, and there’s still Pro and Master to go.

Select Master and the old drift monster returns, with the easy torque and relaxed steering bringing a near-slow-motion experience. It is an astonishing transformation given this is essentially some on-the-fly diff calibration. But even in this mode it remains highly competent at picking apart a quick (dry) road, and I’m astonished just how honest the C63 S keeps the M3, given its seniority. It’s fantastic.

Alfa Romeo Giulia Quadrifoglio: plenty go, some flow

m3 test close chase

Where the C63 S runs the M3 surprisingly hard, the Giulia Quadrifoglio struggles more than expected, but there’s still so much to recommend the Italian. Its recent refresh leaves the lauded dynamics and powertrain as they were (twin-turbo V6 with 503bhp, eight-speed auto, rear-wheel drive), wisely resists taking a scalpel to the Sophia Loren looks, and instead focuses on driver-assistance systems and, more crucially, updating the infotainment.

The Alfa flows down the road with real delicacy, thanks to startlingly quick and communicative steering clearly modelled on Ferrari, a fluid ride quality and the twin-turbo V6 with its fruity, brassy sort of pomp that climaxes with massive performance and flatulent noises that your ears call as gearchanges but your g-sensor says didn’t happen at all. There’s not the low-down punch of the M3 or C63, rather it’s more like shaking a bottle of champagne then popping the cork, but there’s plenty of fun in that and, besides, nothing else on test sounds so exotic and quite so excited to find itself spinning at 6500rpm. Remember too that the Alfa’s also lightest by a margin, and therefore king of the power-to-weight stakes despite a best-equal 503bhp. You feel that in the punch of its performance and how it dances through corners all fingertips and tip-toes where the others claw and grip.

So, the Alfa remains a fantastically evocative car to drive over roads as stunning as these, but the competence of the M3 and C63 expose cracks in its integrity. You’ll note that the cabin is driver-focused and riffs on Ferrari with its long, slender shift paddles fixed to the steering column and start button on the wheel, and those infotainment updates really do enhance the ownership proposition. But the Alfa still clearly lacks a depth of interior quality versus the others, no matter if it’s usefully improved.

c63 giulia pan

On the road it also doesn’t feel as structurally sound, which manifests as more secondary patter at low speeds and a less coherently solid feel than the Merc and BMW. Even on sticky Pirelli Trofeo Rs it can’t match the front-end purchase of the M3 when you roll it into a mid-speed corner, and the driving modes that change the damping, steering and powertrain but can’t be mixed bring out my inner Goldilocks – body control is too loose for the super-quick steering in its softest setting, the throttle is too responsive in Dynamic (especially when it’s almost pinned, where it lacks fine control), and you need to be in Race to have the stability control disabled. Do that and the rear diff takes on a Drift setting, but it’s actually quite indecisive during a slide, with power pogoing between the rear wheels, almost like an open diff.

It sounds like a long moany list of faults, but the Quadrifoglio’s still superb – it just has more flaws.

Audi RS4: different by design

Where the other three aim at largely similar targets, the Audi RS4 ploughs its own furrow, and not necessarily through the nearest field – they’re better than that these days.

The RS4 was updated just over a year ago, and adds an RS6-inspired wider front grille and re-designed matrix LED headlights to a body defined by those muscular blistered wheelarches. But it’s not a radical transformation otherwise, and surprisingly the twin-turbo V6 remains pegged at 444bhp and 443lb ft, so it trails the competition by around 10 per cent – at least it’s barely heavier than the BMW and M3, despite all-wheel drive and an estate body.

Buy an RS4 if you crave maturity. Even the optional sports exhaust won’t turn early mornings into Bonfire Night – instead its subdued warble has a mournful V6 sweetness, and actually it pulls hard, with good response, snappy auto gearchanges and a pretty wide bandwidth (though yes, we still miss the old V8/dual-clutch combo).

rs4 m3 chase

Road noise is well damped, but the aural isolation comes at the expense of any true tactility filtering up from the Contis, and there’s a lazy spot at the top of the steering – good for stability, not so much agility. Apparently 85 per cent of drive can go rearwards, but initially it just feels a little inert, handling in a highly neutral manner without a great deal of fizz. All-wheel drive compounds the lack of excitement and power deficit to the others – it could handle so much more, but it’s certainly sure-footed.
Switching the differential to Dynamic has a surprisingly transformative effect, much like the AMG. It brings the more engaging sensation of the outer rear wheel powering you through a bend and making the front end feel more positive – the rotation thing racing drivers talk about. Interesting to experiment, but given the inherent safety of all-wheel drive with stability control, can anyone rationalise the Undynamic setting?

Fundamentally, though, I get the RS4. Buyers want something understated but not so understated that people don’t notice, they want versatility, build quality and refinement, and they want performance without the excitement of being spat off a mountainside.

But for that buyer, the RS4 falls down on three counts: this remains a very nice interior but its once cutting-edge tech is now bettered by the M3; its gearchange can occasionally upset refinement; and more than anything it’s the ride quality. In the rivals you allow for some firmness because it’s integral to what makes them so engaging to drive quickly, but the Audi simply doesn’t ride nicely enough. There’s low-speed lumpiness, and a lack of primary sophistication over trickier B-roads that has you hacking at the wheel like the big-fish-little-fish-cardboard-box dance. There is possibly a solution to this, given Audi didn’t option this car on DRC suspension, which diagonally interlinks the dampers via a central valve.

BMW M3 vs rivals: verdict

m3 test overhead

We can’t play coulda/shoulda here, so the Audi makes for a pretty desirable last place. For some, individual circumstances might actually flip that order and to hell with a road tester whooping about powerslides in the Peak District. Just try to test it on that optional suspension if you possibly can.

The Alfa Giulia Quadrifoglio bags the final place on the podium. Judged on excitement, it remains a fine substitute for either the C63 or the M3, but the interior comes up short, and a back-to-back comparison reveals its age dynamically – much as the Giulia beguiles with driver appeal and frothy charisma, it doesn’t feel as polished as the others, whether that’s the rigidity of its structure and capability of its chassis, or the calibration of its systems. Fun, though.

That leaves the BMW and Mercedes duelling for the win. I dither between them like choosing a favourite child, simply because both are exciting and feelsome to drive, each scoring points over the other, and the AMG providing surprisingly stern opposition given its age. Ultimately the M3 gets the nod – I find it marginally the more enthralling drive, with a fire in its belly at 7000rpm that’s just phenomenal, a chassis that lifts the bar in terms of grip and poise but still knows how to have fun, and there’s also a greater bandwidth of usability in terms of better-suppressed road noise, and a more modern interior with superior infotainment.

Like Roberto Ravaglia racing the original E30 M3 in ’88, the new M3 simply racks up more points over more rounds to win the championship. The G80 might have more in common with the previous model than any other M3, but to me it now tastes exactly like an M3 should. One day, I hope to buy one.

First place

Second place
Mercedes-AMG C63 S

Third place
Alfa Romeo Giulia Quadrifoglio

Fourth place
Audi RS4 Avant

Read more CAR comparison tests

By Ben Barry

Contributing editor, sideways merchant, tyre disintegrator