Mercedes-AMG A45 vs BMW M135i: war of the worlds

Published: 02 December 2019

► Battle of the 2020 hyper-hatches
► BMW M135i vs Mercedes AMG A45 S
► Which pocket rocket wins our twin test? 

In the Misano Blue corner, the new BMW M135i. In the grey, the Mercedes-AMG A45 S. A pair of 300bhp-plus hyper hatches armed with advanced all-wheel drive, launch control, drift modes and more raw performance than has previously been deemed wise in cars this size.  

How on earth did we get here? When phones were for phone calls and the world was a gentler place, Mercedes made comfortable saloons, estates and variations on the GT theme; BMW did the driver-focused saloons and the odd sports car. Hatchbacks? Volkswagen did those; Ford too. Even when both makers dipped a toe in hatch-shaped waters, each had very different takes: witness BMW’s straight-bat 3-series Compact versus Mercedes’ radical original A-Class. 

But ever since, both makers have been sucked into the same orbit. First to blink was Merc with its more conventional third-gen A-Class of 2013. It paved the way for AMG to create – via a montage involving a barely-lit workshop, arcs of angle-grinder sparks and a brutal industrial-metal soundtrack – the A45 hot hatchback, and take the fight to BMW’s M135i. Buyers might have cross-shopped them, but the two remained mechanically distinct; the Mercedes’ transverse four-cylinder engine and all-wheel drive could not have been more different to the M135i’s longitudinal straight-six and rear-wheel drive – indulgent engineering decisions both, that rightly prioritised how the car drove over how comfortably it could take you and your pals to bridge night. 

But with this new generation, it’s BMW that has put itself on a direct collision course with Mercedes. Not only is the brand new M135i only available with all-wheel drive, it has switched from a longitudinal straight six with 315bhp to a transverse four making 302bhp, too. At this point it’s tempting to throw your hands in the hair, scream in despair and walk away to a hermit’s existence, living on a remote storm-swept island (with decent 4G data coverage) and endlessly re-watching YouTube clips of the old rear-drive M140i (more power, more sideways, more everything). 

BMW M135i hot hatch vs new 2020 Mercedes-AMG A45 S twin test

But hang on a moment. BMW will still sell you a car of that ilk, the old-school M240i. And before we pack an iPad, some crop seeds and a volleyball with a face scrawled on it for company, let’s come at the third-generation 1-series with a little objectivity, shall we? 

Best hot hatches 2020: our guide to the best performance hatchbacks

Wider, longer and taller, yet sporting a slightly shorter wheelbase, the M135i is more pragmatically packaged than the car it replaces, more economical to run and available with more tech. Analyse its genetic make-up and you’ll find more than a little Mini in there. The horror! But – and it’s a big one – this new 1-series is, in more ways than one, the more complete driving machine.

The last car, the M140i, was as tail-happy as Larry, all over the place when pushed and forever on a quest for traction in the wet as endless and as futile as mankind’s search for existential meaning. It was also an engaging and endlessly fun training ground for opposite-lock heroes. The new car trades rowdiness for poise, the sideways for the surgical, and a rip-roaring metabolism for some manners. Allow me to elaborate.

Unlike the exterior (erm, shall we leave it at ‘spec-sensitive’?), BMW’s new cockpit is easy on the eye. Next to the drive-by-wire shifter for the eight-speed automatic, we find the drive mode selection and the latest iteration of the iDrive controller, which gives the left hand something to do when it’s finished exercising the buttons and toggles on the steering wheel.

Paired to the intuitive ‘Hey, BMW’ voice activation, this encouragingly practical approach to ergonomics is complemented by a feast of driver-assistance goodies, including the useful 50-metre reverse-gear memory, which backs the car up and out of trouble by retracing its own footsteps. In combination with the free-flow exhaust and a pair of fist-size tailpipes, the standard ‘active sound design’ system generates all the noise permitted by law. But yeah, you guessed it: in terms of acoustic talent, the four-cylinder can’t hold a candle to the old six. 

On the road in the BMW M135i hot hatch

Whatever; let’s go. Put your foot down and the BMW thumps you in the back. Hard. It’ll hasten from rest to 62mph in a pretty convincing 4.8sec and never feels anything but fast. So far, so good. But it’s when the road begins to twist and turn – as this one on the outskirts of Munich is now beginning to do in the most delectable way – that the M135i really starts to come alive. Maybe, just maybe, Everything Is Going To Be Okay. 

BMW M135i: it might have ditched rear-wheel drive, but it's still mighty sharp

A discreet master of the winding road? Feels that way. Through the meaty steering there is, despite the hefty shunt passing through the same axle, no power corruption and no torque steer. In fact the BMW’s steering is a joy: scalpel-sharp yet superbly grounded, and your key to a world  in which your cornering attitude – apparently irrespective of your entry speed or the available grip – is always deliciously, almost supernaturally neutral. A front end you can work with, plus an electronically-finessed chassis that always seems at least one step ahead, hooked up and ready to do your bidding? You got it.

The upshot of all this? The M135i takes BMW hot-hatch handling, roadholding and performance to a higher level, creating what is by a country mile the most chuckable 1-series yet. Yes, the battleship grey AMG still looms so large in my mirrors that it must look like I’m towing it, but the A45 S’s towering power advantage – at 415bhp it’s the world’s punchiest production four-cylinder engine! – means that was always going to be the case. The truth is the AMG’s driver is having to work hard to stay with me. This BMW is sensational.

I can’t remember where, when or even if we’re supposed to be stopping to compare notes, so I just drive on. The tarmac, wet in places and lethal with oil-slick sap from overhanging trees, never stops darting left and right and left again, dips and blind crests waiting like patient anglers for their first catch of the day. But they’ll never catch this thing, the M135i dancing into corners with a grace entirely at odds with its dumpy aesthetic before hammering out of them with a WRC-inspired combination of lag-free turbo thump and deft, nuanced all-wheel-drive traction. 

BMW M135i interior

The M135i is a carver, not a scrubber. As soon as you turn the wheel and start reeling in the apex, the BMW assumes a flat yet responsive stance. From corner entry to exit, a pliable quasi-drift is executed by steering, throttle and chassis with cool calculation and efficiency. Throw it into a bend as you would Billy the black lab’s favourite stinking tennis ball and the BMW quickly sorts itself out, tightening or relaxing your line as required and either asking for more input or substituting for it if further commands are not forthcoming.

It goes where it’s pointed, fusing accelerator position and steering angle into the fastest possible vector. Boring perfection? Are you kidding? It’s brilliant. Surreal, granted, and more digital than your BMW-loving father or grandfather would like, but that’s their loss. Quite brilliant and incongruous too, given how benign and supermarket-car-park the M135i looks. 

Mercedes-AMG A45 S: the ultimate hyper-hatch?

Like your budget-busting hyper hatch with more of a sense of occasion? Perhaps AMG can help. Relatively demure here, the A45 S can be spec’d up to look like a racing car from the DTM feeder series of your dreams: egg-yolk yellow or Maranello red paint and more carbonfibre aero parts than Adrian Newey’s spare room. It looks menacing in a way the BMW just doesn’t – and backs that up with big numbers. It’s an eye-watering £50,570 for the S tested here (non-S AMG 45s won’t come to the UK) and that monstrous 415bhp from the 1991cc four. Barely any heavier than the BMW, the AMG duly monsters it off the line, come rain or shine, being nearly a full second faster 0-62mph at 3.8 seconds.

Impressively, like the more affordable A35, this dinky and expensive Fabergé egg of a hyper hatch feels more like an AMG than a Mercedes. That same thrill/sense of trepidation as you climb aboard, the seats gripping you as images of thundering Red Pigs, sideways Black Series cars and car-sized holes in roadside fences run through your mind. It feels exotic in here, nearly as expensive as it actually is, and serious, even if cabin quality is concentrated in the bits you see most often. 

Mercedes-AMG A45 S: this or a BMW M135i?

Powering out of junctions and racing between corners, the AMG feels every bit as potent as the numbers would suggest. Its performance is of a different order of magnitude to the BMW’s, and the way the A45 S makes its power and uses it to fire itself up the road is somehow grittier, more physical and more involving than the rapid but more refined BMW. 

Having previously lobbed the AMG around the Jarama circuit and surrounding roads for the press launch, I know how best to calibrate the 45’s myriad drive mode options: Sport+, with dampers in Sport on the road, for a little real-world pliancy, and the hard-working, appropriately punchy transmission in manual. Plain old Drive does a fine job holding the correct gear, shifting down just in time and making full use of all 7000rpm, but there’s a time and a place for the racier settings and it’s now, with the blue BMW making hay up ahead.

The AMG’s middling stability-control setting encourages the odd lift-off tail wag, as well as momentary traces of exit oversteer, which is most likely all you’ll feel comfortable with in an environment dominated by blind corners, question-mark crests and unannounced surface changes. And if talk of such an animated chassis comes as a surprise, you’re forgiven. Previously, like Audi’s similar-in-ethos RS3, AMG’s A has been big on power, short on playfulness. But with uncanny timing, given the all-wheel-drive BMW’s arrival, that has changed. Spray the Moët. 

Author Georg Kacher drives the Mercedes-AMG A45 S

You can sample the A45 S’s new-found sense of silliness at its most extreme in Drift mode. Transmission in manual, drive programme in Race, ESP off. Now, pull both shift paddles simultaneously, then confirm powerslide mode with a quick flick of the upshift paddle. Ready? Now set about murdering your rear tyres and trying to remember that, despite the  effortless, creamy ease with which the AMG will lazily hang its rear end out of line, the hatch dancing like a pedigree drift machine so long as you maintain a tighter-than-normal steering angle (dial in opposite lock, as instinct dictates, and you kill the slide dead) and a generous amount of the throttle, you really are driving an A-Class. 

Steering, dynamics and handling

The Merc’s steering can’t match the BMW’s for accuracy, and neither is its front axle quite so miraculously understeer-proof, but it’s faster and  delivers a more satisfying sense of connection. The AMG’s electro- mechanical, rack-and-pinion set-up is variable-effort and variable-rate – ordinarily a pretty reliable recipe for artifice and profound numbness. Not so here. The effort changes progressively, while the calibration alters between swift, stiff, relaxed and balanced in accordance with the selected drive mode. In Sport+ it’s both responsive and nicely weighty, well up to the job of both telling you what the front tyres are up to and quickly firing in the lock should you need to keep the now mobile rear end in check. 

Just as BMW promises no understeer or torque steer with the new M135i, Mercedes claims a totally neutral handling attitude and no power-corruption of the 45’s steering. Cobblers? With more than 100 additional horsepower wedged between its broad shoulders, the AMG can perhaps be pardoned for a couple of inches of third-gear understeer at the limit. It’s useful. Without it, you wouldn’t be as confident to fly the AMG without an electronic parachute, or to dig deeper into what is a deeply impressive, very rewarding car.

BMW M135i twin test against the new Mercedes-AMG A45 hot hatch

Although discreet, the AMG’s torque distribution is never fully isolated from your palms, relaying information without interfering. As with the BMW, the AMG’s drivetrain is a complex system that feels entirely intuitive and malleable from the driving seat. On both sides of the rear differential sit electronically-controlled clutches, one for each driveshaft. In combination with the variable electro-mechanical front-to-rear torque split, this variable rear side-to-side torque distribution ensures optimum traction – except of course when you deliberately dial in compromised traction… Sounds relatively straightforward, but the chip-controlled network of sensors and control units could not be more complex. 

On the road, spectacularly potent engine ripping past slower traffic and dropping the BMW in your mirrors like the driver has (somehow) missed a gear, the AMG’s baffling tech translates to a deliciously simple, almost analogue whole. There’s always power, except when a couple of very rare combinations of throttle position and gear selection conspire to mean that, for the blink of an eye, there’s the merest trace of turbo lag instead. Torque below 3000rpm is adequate; heavyweight beyond that. The brakes, on the road at least, are similarly unwavering, though track use soon gives them a pretty unpleasant roasting.

But it’s the AMG’s neutrality and malleability that are the outstanding qualities here; the interactivity absent in its predecessors and that now make the smallest full-house AMG as desirable as the bigger C-Class and E-Class 63s. The ultimate A-Class has long been able to summon a feelgood smugness born of its premium badge, slick  tech-start-up-meets-GT3-car interior and giddy, addictive power. But this new A-Class can chisel a very broad grin onto your face for the way it drives. And that is progress. 

This is not your classic winner-takes-all comparison. Performance cannot be the sole decider, or this story would end right here. The numbers take a back seat to subjective impressions. The bum-dyno replaces the stopwatch, shameful filling-station receipts are binned with an impish grin and our driving licences are soaked overnight in Holy water. And the truth is we – the male faction of the Kacher family, including sons Max and Sebastian, raised on an octane-infused formula – have a blast. The rally-inspired hyper hatch is here. And it’s quite something.

Merc A45 chases the BMW M135i in CAR magazine's twin test

Final verdict: the genius of the baby AMG

It hasn’t escaped our notice that there is a Mercedes-AMG A35; a car far closer to the M135i in most respects than the 45. But this is about ultimate evolutions – the best of the best – and, on this evidence, that’s the AMG A45 S. And yes, much of that superiority can be found under the hood; Merc’s engine is more potent, sounds better and is more refined, while its gearbox has a sadomasochistic physicality that never gets boring. 

Break it down and the Mercedes goes on taking scalps. The A45 S rides better; compliant, with no rough edges except where they belong. Dial things up and the AMG’s Race setting is much wilder than the M135i’s Sport, the Benz steering more quickly and feeling better connected. 4Matic all-wheel drive can play more tricks than xDrive. But the BMW fights back by banishing the eternal vices of understeer and torque steer.

Inside, MBUX is smarter than ‘Hey, BMW’. But both are stuffed fake goodies you rarely need, not to mention a bunch of grating assistance systems, too many sub-menus and not enough direct-access functionality. This is what happens when marketing, design and the supplier community go drinking and the customer pays the bill.

And on the outside? The M135i does look better in the flesh, especially side-on and from the rear. In fact, only side-on and from the rear. The A45 is prettier and feels nicer inside, but the patchy quality disappoints. The exterior is pure AMG, for better or for worse – the public’s appetite for tolerating such automotive ostentation is waning, which may or may not bother you. No one will even notice your M135i.

BMW M135i costs £36,430; Mercedes-AMG A45 S price is £50,570

Value for money? Let’s face it, both require serious dedication to the acquisition of the very latest and greatest. Instead of this BMW, consider a lightly-used rear-wheel-drive M140i with the manual transmission – and donate the rest to charity. Or start looking for a low-mileage C63 AMG estate which will consume less fuel when pushed and was born to drift.

Undeterred? Good. The truth is, both are hugely talented cars – pint-sized exponents of the art of fast, very satisfying all-wheel-drive performance that Porsche 911 Turbo pilots have been getting high on for years. For the record, BMW has not ruined the fast 1-series. But neither has it yet built a car – M2 Comp included – to touch AMG’s A45 S.  

More comparison tests by CAR magazine

BMW M135i specs and information

Price £36,430 (£44,780 as tested)
Representative PCP £450pm (47 payments): £5000 deposit, 10k miles per year, 4.9% APR
Typical approved used value £31,020 (10,000 miles, no options)
Engine 1998cc 16v turbo four-cylinder
Transmission Eight-speed auto, all-wheel drive
Power 302bhp @ 5000rpm
Torque 332lb ft @ 1750rpm
Top speed 155mph
0-62mph 4.8sec
Structure Steel
Weight 1525kg
Suspension MacPherson strut front, multi-link rear
Length/width/height 4319/1799/1434mm
Boot capacity 380 litres
Fuel capacity 50 litres
Official economy 34.4-35.8mpg
During test 17mpg
Range 378-394 miles (187 miles on test)
CO2 155-157g/km

Mercedes-AMG A45 S specs and information

Price £50,570 (£56,450 as tested)
Representative PCP n/a (too soon)
Typical approved used value n/a
Engine 1991cc 16v turbo four-cylinder
Transmission Eight-speed twin clutch, all-wheel drive
Power 415bhp @ 6750rpm
Torque 369lb ft @ 5000rpm
Top speed 169mph
0-62mph 3.9sec
Structure Steel
Weight 1560kg
Suspension MacPherson strut front, multi-link rear
Length/width/height 4445/1850/1412mm
Boot capacity 370 litres
Fuel capacity 56 litres
Official economy 32.5-33.6mpg
During test 15mpg
Range 400-414 miles (185 miles on test)
CO2 189-192g/km

Mercedes-Benz's A45 fights the BMW M135i in CAR magazine's exclusive comparison test

By Georg Kacher

European editor, secrets uncoverer, futurist, first man behind any wheel

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