Mercedes-AMG SLC43: Review

Fury, outrage and pure disgust are just some of the ways PHers have reacted to Porsche slicing two cylinders and nearly a third of cubic capacity offย the Boxster's flat-six engine. Sure, it's gained a fancy turbo and a bunch more mid-range but, even with a sports exhaust, that seemingly isn't enough to drown the howls of protest. Odd then there's been barely a whimper at Mercedes-AMG killing off its last naturally-aspirated V8 and replacing with a twin-turbo V6.

Perhaps it's all about context. There's been a V8 under the bonnet of the SLK for more than 12 years. Yetย the SLK55 AMG has been overlooked almost its entire life, even by supposed enthusiasts like us.

Given the strength of the competition from Porsche, BMW and others you'd seemingly be mad to choose the Mercedes. But madness is precisely why everyone should mourn its demise. How can you not admire a manufacturer that crammed aย ย 421hp 5.5-litre V8 into a tiny roadster? Better still, the V8 loved to rev, offered a hard-edged soundtrack and mid-range acceleration that was almost as shocking as its ragged on-limit handling.

V8 out and V6 in - a good move?
V8 out and V6 in - a good move?
Forgotten hero
Others may have traded on looks or handling finesse but the SLK55 was all about grunt. And totally at odds with the SLK demographic, stereotypical or actual. It shouldn't have existed but somehow AMG convinced Mercedes suits it'd be worthwhile re-engineering the usually twin-turboย M157 5.5-litre V8 into anย M152 normally-aspirated version specifically for the SLK. AMG wanted to keep a big V8 under the bonnet of the baby roadster so badly it even included cylinder deactivation to deliver reasonable official figures of 33.6mpg and 195g/km. Still not enough though, and it's time to bid farewell.

The replacement has been timed to arrive with the first big facelift of the third-gen SLK since its launch in 2011. Rebadged SLC, Mercedes is once again making life complicated by giving it a nameย most will associate with the slow, thirsty V8-powered coupe derived from the 'Dallas' R107 SL. Adding the confusion is the fact the 3.0-litre twin-turbo V6 gets the newย '43 nomenclature - a number any right-minded PHer will associate with a very tasty V8 follow-up to the original C36 AMG.

Anyway, in comes a comprehensive nose job including an SL-style upright grille and new LED lamps front and rear. Inside there are new, higher quality materials and lots of new safety kit like autonomous emergency braking. So far, so dull.

New name, but the style is familiar
New name, but the style is familiar
Carrying a torch
What is interesting, however, is how much time and effort has been lavished on the SLC43 to make it worthy of succeeding the much-loved (even if only among AMG engineers) SLK55. First hurdle was power and torque. The 3.0-litre V6 twin-turbo can only muster 367hp - 54hp down on the V8. What AMG should have done was sneak the 510hp 4.0-litre V8 twin-turbo under the bonnet. But that would have made it as quick as an AMG GT S, which would have been politically difficult.

Luckily, much of the power deficit is hidden by the new quick-shifting nine-speed 9G-Tronic gearbox. The result, along with a 30kg weight-saving, is a 4.7-second 0-62 sprint just a tenth slower than the V8. Infuriatingly, despite claims that the old V8 was pensioned off for efficiency reasons, the new turbocharged V6 is only fractionally improved, bettering the old car by a measly 2.6mpg and trimming just 17g/km off the CO2 figure.

There's better news in the chassis upgrades though. These include binning the old car's front suspension and basing the new set-up around front struts from the previous C63 AMG. Tyres are, by modern standards, modest 255/35s on 18-inch wheels but there are stiffer suspension knuckles and a tad more negative camber to help reduce understeer.

Noise can't quite match V8, but it's good
Noise can't quite match V8, but it's good
A la mode
For the first time there's also the option of adaptive dampers with the combined benefits of a more relaxed ride in Comfort mode and better body control in Sport and Sport+ settings. At the rear of the car the old V8 rear axle carries over with a standard limited-slip diff for UK cars.

By a quirk of fate the French test route takes in the same roads I sampled the first SLK55 on back in 2004. And the difference between the two is huge. Quiet and with a layer of sophistication completely lacking in the last AMG version, the '43 even rides well.

Some stabs of the throttle release some raspiness but it's flicking to Sport, and then Sport+, that helps the small SLC start having some fun. When I say 'some fun' I mean get really, really loud, with dramatic pops and bangs that are fun, admittedly, but ultimately synthetic compared with the V8.

Things rapidly improve as we begin our slow ascent into the mountains. Both steering and front grip are transformed. The steering is more precise and accurate, offering confidence to push harder. Upping the pace the elasticity of the twin-turbo V6 shrugs off any concerns it's lacking in the power department. In fact, it hurtles to the redline so keenly you have to be quick with the gearchanges to avoid brushing the limiter. Upchanges feel almost as fast as dual-clutch. Shame it's not so fast on the way back down though, the nine-speeder reluctant to give the gear you want and slow to shift when it eventually consents.

The biggest obstacle to overcome is the ESP. With a sharper front end and a short wheelbase it's sufficiently paranoid about snapping into wild oversteer it kills power and applies the brakes as soon as you feed the power in out of a corner. It's better in the Sport handling mode and there's a fully off setting for heroes, actual or wannabe.

Nine-speed auto good on the way up, not going down
Nine-speed auto good on the way up, not going down
Wobble, wobble
By now the roads are morphing from flatteringly smooth to something more familiar to British drivers. Throw in the odd bump, crest or camber change and the SLC feels less sharp as the steering rack gently quivers in your hands. Slowing to raise the roof - now possible at up to speeds of 25mph - and the rack wobble is accompanied by creaks from the hardtop. While we're complaining, the cabin also feels its age and the sat-nav throws up confusing instructions.

Roof back down and the brisk cross-country pace continues. It's clear the less powerful '43 feels easily as quick as the car it replaces. But would you have one over a 718 Boxster S?

Lopping two cylinders off the AMG has seen prices slashed. The fastest SLC now costs ยฃ46,355, down from the towering ยฃ56,000 Mercedes demanded for the old SLK55. That makes it more than ยฃ6,000 cheaper than a PDK-equipped 718 S.

Improved, but less appealing without that engine
Improved, but less appealing without that engine
The new Boxster wins back almost all that advantage by being even quicker still and more rewarding by pretty much every dynamic measure you could offer. However, for those who feel the switch to just four cylinders is a step too far in the charisma department, the SLC43's more appealing sound and feel might just compensate.

Saying that, if it was us, we'd get a move on and make an offer on the outgoing SLK55. It may be flawed and a little less capable but - in a familiar pattern - the madness and charisma of a huge normally-aspirated V8 in a small roadster is something we'll all miss.

2,996 twin-turbocharged V6
Transmission: 9-speed auto, rear-wheel drive
Power (hp): 367@5,500-6,000rpm
Torque (lb ft): 384@2,000-4,200rpm
0-60mph: 4.7sec
Top speed: 155mph (limited)
Kerbweight: 1,595kg (EU, with driver)
MPG: 36.2 (NDEC combined)
CO2: 178g/km
Price: ยฃ46,355









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Comments (38) Join the discussion on the forum

  • sidesauce 07 Apr 2016

    People laughed and called it a hairdressers car.

    Personally I think the SLK55 was a woefully underestimated car and now Mercedes has followed the market trend for downsizing we will never see its like again. A large capacity N/A V8 in a car of that size? Madness, and all the better for it!

  • Deerfoot 07 Apr 2016

    I had a go in a 350 SLK a while back and loved it.

    I wish manufacturers would get over this silly obsession with matt paint. It looks utterly naff...

  • Cupramax 07 Apr 2016

    Quite liking this, also so much for the new 4 cyl boxsters efficiency, this produces less of the dreaded c/o. £10k cheaper than the old one albeit no longer v8! Winner. Give it a manual box and id be tempted.

  • Atmospheric 07 Apr 2016

    I think it just shows a better attitude to engineering generally from Mercedes. But, I'm not sure we should be surprised at all by this given their rich history.

    I'd have this over "that" Boxster S, despite the Porsche may be better balanced. What is "better" anyway? 6 over 4 all day long.

    The price is also reduced - Porsche take note.

  • HJMS123 07 Apr 2016

    genuine question .... why do Mercedes persist on using their own boxes and not something which is proven to work well like the ZF?

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