Key considerations
- Available for £47,000
- 2.0-litre inline four petrol twin-scroll turbo, all-wheel drive
- World’s most powerful production four-cylinder engine
- Lots of equipment, decent boot, distinctive styling
- Built to take a beasting, and tuneable
- No bargains to be had
Like the thought of being able to tell your mates that your car has the world’s most powerful four-cylinder engine? Then take a deep breath, not only for the money you’ll need to get that car but also for the length of its name. We’re talking about the Mercedes-AMG CLA 45 S 4MATIC+ four-door saloon, or coupe as Mercedes sometimes liked to call it. Of course, if you have the wrong sort of mates one of them might pipe up and spoil your day by tossing the keys to a Mercedes-AMG A 45 S 4MATIC+ hatch onto the table. Same engine, different body shape.
Based on the gen-three W176 A-Class, the first A 45 AMG of 2013 made instant headlines for its mad power figures. Mercedes-AMG needed to go in hard with the A 45 and CLA 45 as they couldn’t very well make a grand entrance into the scaldingly competitive hot hatch (and less competitive four-door hot saloon) market with something weedy. The first 2.0-litre M133 all-aluminium turbo four made a suitably emphatic statement. Its 355hp/332lb ft output allowed the A hatch and CLA coupe/saloon to claim the same 187.5hp-per-litre power figure as the Bugatti Chiron. By way of comparison, the 2.0 turbo four in Volkswagen’s contemporary Mk7 Golf GTI was putting out 227hp and 258lb ft.
More nose-rubbing was on the menu for Volkswagen and every other hot hatch manufacturer when, in a mid-2015 facelift, the 45’s numbers went up to 375hp and 350lb ft. The power hike – an ‘anything you can do’ response to Audi’s release that year of its 362hp RS3 – plus some gear ratio revision and the addition of new driving modes reduced the 45’s 0-62mph time from 4.5 to 4.2 seconds.
More than impressive enough for a 2.0-litre four, you might have thought, but AMG wasn’t done yet. For the 2019-on second-generation C118 model unveiled at the 2019 Goodwood Festival of Speed there was a new 2.0-litre M139 engine which was turned through 180 degrees, putting the turbocharger behind rather than in front of the main motor unit to allow for the most aerodynamically efficient front-end body design. Thus equipped, the new CLA 45 S produced 415hp and 369lb. S was the only spec available in the UK. That’s the car we’re looking at in this guide. For information, non-S gen-twos sold in other markets were rated at 382hp/354lb ft, so that was a win for the UK, although there was a sting in the tail when it came to the sticker price which we’ll get to in a minute.
At this time (mid-2019) Mercedes announced an X118 Shooting Brake version of the CLA 45 S, previewing it at the 2019 Geneva Show for sales in the UK beginning in 2020. Like the saloon, it was quick and easy to drive, knocking off the 0-62mph run in the same 4.0 seconds and 0-60mph in 3.7 seconds. That was less time than the AMG C63 or the RS4 Avant needed to achieve the same feats, but the CLA 45 S wagon’s compactness limited its usefulness as a load-carrier, blunting its appeal, as did its price of nearly £60k before extras. The basic CLA 45 S was a few pounds over £52,000.
There was an S Plus version with model-unique cross-spoke 19-inch wheels, more aero including canards and a bootlid spoiler, LED adaptive headlights, seat massage, 12-speaker Burmester audio, traffic sign recognition and blind spot warning. This S Plus model was priced at just over £58,000.
Apart from the obvious physical ones, there were a few small differences between the CLA 45 and the A 45. They had the same wheelbase but the CLA had wider tracks front and rear than the hatch. It was also marginally lower (5mm) and a fair bit longer (nearly 25cm). That extra bodywork made it noticeably heavier than the A 45 (1,675kg vs 1,635kg, or 1705kg for the Shooting Brake). The CLA also had slightly wider tyres (255) on 9.0-inch wheels rather than the A’s 245s on 8.5-inchwheels, but the drivetrain and cabin were the same for both cars. The CLA’s boot was larger at 470 litres versus the hatch’s 455 litres but of course you couldn’t boost the CLA’s boot space appreciably by dropping the rear seats like you could in the hatch.
The CLA 45 S’s brilliant 8-speed dual-clutch AMG SpeedShift DCT transmission and continued use of 4MATIC all-wheel drive – with torque-splitting between the rear wheels via a new Torque Control rear axle that put electronically controlled clutch packs into the differential – gave it scorching launch potential, talon-like grip through corners, and drifting on demand.
SPECIFICATION | MERCEDES-AMG CLA 45 S/S PLUS 4MATIC (2019-on)
Engine: 1,991cc inline four 16v twin-scroll turbocharged petrol
Transmission: 8-speed dual-clutch auto, all-wheel drive
Power (hp): 415@6,750rpm
Torque (lb ft): 369@5,000-5,250rpm
0-62mph (secs): 4.0
Top speed (mph): 168 (limited)
Weight (kg): 1,675
MPG (official combined): 34.9
CO2 (g/km): 186
Wheels (in): 19
Tyres: 255/35
On sale: 2019 - on
Price new: £52,000 (S), £58,000 (S Plus)
Price now: from £47,000
Note for reference: car weight and power data are hard to pin down with absolute certainty. For consistency, we use the same source for all our guides. We hope the data we use is right more often than it’s wrong. Our advice is to treat it as relative rather than definitive.
ENGINE & GEARBOX
The idea of a 2.0-litre four producing over 400hp would have seemed crazy not too long ago but the M139 made this bonkers concept real in 2019. AMG wasn’t the sort of outfit to put decades of engineering credibility at risk, so the CLA 45 S motor was built to take hard use with better cooling for both engine and turbocharger courtesy of an over-engine ducting system, roller bearings for the large twin-scroll turbine, high-spec valvegear and injection components and a baffled sump. Every engine bore a badge with the name of the AMG engineer who would be up before the beak if things went wrong.
The M139 was different to the preceding 350hp and 375hp M133 units, not just in terms of its extra power and torque but also in terms of where its maximum torque lived. Whereas the M133s produced their max torque of 332 and 350lb ft across a near-3,000rpm range from 2,250 to 5,000rpm, the 415hp M139’s 369lb ft didn’t arrive until 5,000rpm and the dyno line started heading downwards 250rpm later. The 2023-on M139L engine is even more extreme, its 250rpm max torque band now not starting until 5,250rpm, even though its power and torque haven’t been increased.
With max power coming in at 6,750rpm on the CLA 45 S you might look at the numbers and reach the conclusion that it was hopelessly intractable, but that would be to forget how much spare capacity you had in a 400hp+ car. The days of lag caused by big turbos – even one like this, which can blow at more than two bar – are long gone. There was more than enough go available at lower engine speeds.
It did like to rev though. Quad tailpipes distinguished it from the twin-tailpipe CLA 35, although in fact there was only one main pipe running to each side of the 45, just as in the 35. Not everyone wanted their car to make a load of snap, crackle and pop noises but if you were that person the CLA 45 S would do you proud, serving up a raucous symphony of mechanical commotion whenever the gearbox was being worked and the exhaust valves were open.
The Audi RS3 was arguably more characterful than the AMG thanks to its extra cylinder, but for a four-cylinder car, the Merc was not short on aural drama. It didn’t have a soft limiter either so you could rev it to the redline without going anywhere. Having said that, new noise regs made the S quieter than the old pre-2019 model. If you wanted to wake up more people, an AMG Performance exhaust sat expensively on the options list.
Fuel consumption figures in the high 30s were not difficult to achieve if you weren’t tempted to razz it everywhere – but that was a big ‘if’ on this car. Even in auto mode, pickup on a sudden application of full throttle was instant and addictive. If it wasn’t enough then a Stage 1 ECU reflash for around £800 would take the power up to nearly 490hp and the torque to 485lb ft.
There were a few issues with the turbo, injectors, engine oil consumption and gearboxes on early gen-one A/CLA 45 engines. The turbo’s absence of an anti-surge valve forced excess pressure to exit via the impeller, bringing premature wear, and there had to be a recall on DCT transmission assemblies where a welded seam could fracture, causing a loss of drive. Around half a dozen American-spec 2019-built gen-two 45s had trouble with ‘incorrect’ spark plugs breaking up and falling into the combustion chamber but as far as we can tell the mechanical reliability story has been worry-free for CLA 45 S owners.
Crashed cars could become prone to electrical problems which would be expensive to put right, so an OBD check on any car you might be thinking of buying would be common sense. Standard annual ‘A’ services by a recognised independent should be under £250 and a ‘B’ not much more than £300. For a two-service plus one MOT ServiceCare plan you’d be paying the official M-B AMG dealership network £112 a month, or £168 a month for a three-service/two-MOT package.
CHASSIS
Nothing to complain about in the chassis department. Three-mode adaptive dampers were standard on the UK S models, along with a lovely AMG strut brace between the front shock towers (just one of many braces) and, complementing the CLA 45’s limited-slip differential at the front, a Torque Control rear axle. The extra weight this kit put at the back of the car might have sounded like a bad thing until you drove the 45 and realised that it enhanced the sensation of it being rear-driven.
Up to 50 per cent of the power could be sent to the back wheels, with up to 100 per cent of that being divertible to either wheel with Drift mode engaged. Then, to impress your friends and confound your enemies, you simply mashed the throttle on the entry to a corner and, well, drifted. The amount and cleverness of the traction control trickery gave you a big safety cushion.
In Comfort, the ride quality was firm but far from harsh. Twirling the drive mode dial on the steering wheel to Sport or Sport+ enabled manual mode and opened up the road for fun a-plenty. The steering was sharp, pointy and well-judged, and underpinned by tons of grip. It felt perfectly sorted for UK roads.
360mm six-piston discs at the front and 330mm discs at the back gave the CLA 45 S a sub-50 metre stopping distance from 70mph, which was mighty. Tyre noise was present most of the time but if you were driving it correctly tyre noise would come a poor second to mechanical noise.
INTERIOR
The CLA’s interior was not the work of a shy designer. Some took the view that there were better-built rivals in the market, but AMG’s influence brought more real metal into the cabin, which added a feeling of quality. Roughly-used cars could end up with scruffy seat bolsters.
The CLA’s widescreen version of the MBUX (Mercedes-Benz User Experience) infotainment system incorporated gesture control and a ‘Hey Mercedes’ voice-controlled assistant. Augmented Reality sat nav put a real-time video up alongside the normal map graphic making it pretty much impossible to miss a turn. There was a Drag Race timer too plus Telemetry and Track Pace functions for racetrack shenanigans if you found yourself near to one of the circuits embedded on the hard drive. If it wasn’t on the standard list you might very well be able to import it.
On top of that, you had a full-colour head-up display, adaptive cruise, and active steering and brake assist. A fair bit of trackpad-clicking and diving through menu levels was needed if you wanted to disable some of the potentially annoying safety functions like lane-keeping, but in general, the CLA’s cabin environment was pleasantly and stylishly functional with enough physical knobbery on hand to satisfy most users.
Unsurprisingly, passenger space in the CLA 45 S’s curvy body wasn’t as generous as it was in the regular A 45, especially in the back where legroom was restricted both longitudinally by the excellent (if you were in the front) front sports seats and laterally by space-robbing door pulls. A panoramic sunroof was available to help reduce the slight sensation of claustrophobia some passengers might experience. The 460-litre boot held a fair bit but the aperture for loading stuff in there wasn’t massive or particularly well-shaped.
Recalls were carried out on the CLA range (not just the 45) to fix faulty airbags and aircon systems and rattling seatbelt mechanisms. There was no recall however for an ambient interior lighting fault that cropped up when some CLAs were in motion. In at least one case the fix for this involved some fairly serious stripping out of the dash, door and underseat wiring.
BODYWORK
The CLA’s ’computer mouse’ body shape gave it a mini-CLS look which you either loved or hated. The offside front vent was real but the nearside one wasn’t. Neither of the rear ‘vents’ did anything other than look venty.
Rust protection has always been excellent on these AMG 45s but the black paint on the S alloys didn’t stand up that well to stone attack. The standard (ie free) paint colours were solid white and, oddly, yellow. Others, including a metallic white, were £600 extra, or a £2,000+ extra if you went for a ‘designo’ finish like Mountain Grey Magno. That’s Magno, not Mango.
PH VERDICT
The CLA 45 S delivered a rich feast of speed, talent and driver engagement. Some might say it had a more mature appeal than the A45 S hatch, and we wouldn’t disagree with that, but that doesn’t mean to say it’s boring. Far from it. In colours like matte grey, it looks amazing. The engine backs up the visual promise and in Race mode it will never fail to make you giggle. It’s a strong car too, and with the AMG provenance it seems built to last. That impression is being reflected in high secondhand prices.
The 301hp CLA 35 did a fair impersonation of the CLA 45 act for a lot less money but it was more than 100hp down on power and one cog short in the gearbox. Realistically if you were after a used high-power AMG CLA you’d surely always be wanting the full-fat version, but in that case you’ll also need to be ready to shell out a lot more money for the privilege – at least £10k more for a 45 than a 35, like for like, depending on age and mileage.
At the top of the used CLA 45 tree you might be asked for as much as £60k-£65k, as per this sub-1,000 mile 2023 but the good news (sort of) is that you can join the 415hp CLA 45 S fraternity for around £47k. Here’s a 54,000-mile Plus from 2019 at £47,490. Still a lot, but this is still a newish car and as we say it’s showing itself to be highly resistant to depreciation.
You could actually dip under the £45k mark if you were prepared to accept a damaged/repaired car like this 2020 S Plus Shooting Brake at £44,995. At the time of writing, this was not only the most affordable CLA 45 S in the UK, it was also the only CLA 45 S Shooting Brake anywhere in the UK. Rare beasts.
1 / 10
