SLK55AMG

http://www.channel4.com/4car/road-te...lk-55-amg.html

There was a time when AMG pledged to make no more naturally-aspirated engines. It was on the launch of the S55, E55 and diesel C-class Sports Coupé (a tyre-smoking diesel, great fun). That pledge has obviously crumbled, because here is the AMG interpretation of the new-shape SLK complete with blower-less 5.5-litre V8.

It has the same capacity as the supercharged version found in the AMG-enhanced S-Class, E-Class, CL and SL, and now in the CLS, but the lack of forced aspiration sees power drop from 476bhp or so to 360. Torque dips too, from 516lb ft to 376.

Should we feel short-changed? Not really; AMG couldn't let the SLK upstage the SL, and 360bhp is plenty for a compact sports car. So the notion of a 476bhp SLK will have to remain a rather violent dream for the moment. Maybe Brabus will do one, and trigger a worrying brand corruption among souped-up Benzes.

The last AMG-tuned SLK had a supercharged 3.2-litre V6, but Euro IV emissions rules were against it. That's why the new one goes the big-bruiser route. The question is, does such a hefty lump of engine compromise what is a very sweet chassis, all the sweeter with a four-pot than with a V6? Piling in a V8 will surely tip the balance yet further away from the optimum.

Not that such thoughts are uppermost as you bellow off into the distance, surprised and delighted at the pace (0-62mph in 4.9 seconds) and the sound effects. You could almost be driving a mini-Corvette - but does a Corvette have such stout body rigidity? With the metal folding roof latched to the windscreen, this feels an entirely solid coupé, and even with the roof folded, draught screen erect and AirScarf™ activated for a warm neck, this SLK feels all of a piece. And that's despite the AMG additions of lower and stiffer suspension, thicker anti-roll bars and 18in wheels. Those at the rear are 8.5in wide and carry 245/35-section tyres, while the 7.5in fronts bear 225/40s.

These suspension changes answer the chassis-ruining question in the negative. This is a taut, wieldy and highly entertaining device. with quick and meaty steering and lots of scope for nudging the tail out. The Mercedes ESP system never goes completely off-duty even when you've pressed the kill button, but on the road it matters little. Here is a compact Mercedes sports car with a focus and a firepower we've not seen before in the genre. It woofles contentedly when asked, crackles into life when goaded.

It looks keen, too, if a bit overdone with its louvres ahead of the front wheels, those strange sill-bulges ahead of the rear wheels and an uncomfortably aftermarket-looking design for the wheels themselves. This is all a matter of taste, and it's not mine.

More of a problem, though, is the '7G-Tronic with AMG Speedshift'. First, seven gears in an automatic gearbox is too many when you're using manual mode. You get lost in the sequence, and besides an engine this torquey doesn't need so many ratio steps. And it's not as if they're usefully spaced, because there's a big gap between fourth and fifth followed by two more gaps of minimal significance.

Worse, for all the talk of 'superlative driving dynamics' when using the manual mode - no unwanted auto-shifts up or down, proper engine braking - the shift never quite happens when you want it. There's always an indeterminate delay. We drove the SLK around the Paul Ricard test track, Formula One's high-tech racing laboratory whose long, tightening curves reward technical skill far above instinct (have we just stumbled on what might be wrong with F1 today?), partly to reinforce the link between this AMG and its close relative, the SLK 55 AMG F1 pace car. And, in manual mode, this automatic transmission was a real impediment.

It doesn't change down exactly when you want, but some time later such as when you're starting to turn. You can imagine what that does for the chassis balance. And when it does change down, it can put such a drag on the rear wheels that stability is compromised. It makes no effort to match the engine revs to the new lower gear, and it thwarts attempts to do this yourself with a blip of the throttle. All in all, you never quite know where you are with this gearbox in manual mode, which is bad news on a track.

So you're better off in auto mode, which is a sad indictment. And then you have the possibility of an unbidden downchange as you power out of a corner, and the balance goes to pot again. It's a shame about all this, because otherwise the SLK 55 AMG showed up well on the track: good grip, tight body control, pleasing natural balance, natural-feeling steering, ample braking power from the two-part front discs (the braking surface is decoupled from the aluminium hub to allow for expansion, and is gripped by six-pot calipers). But if ever a car needed a DSG gearbox, or even - yes please! - a proper manual, it's this one.

Sales start in December at £47,730.

scorchie

I'm not sure about the other members of these forums, but I drive my cars mostly on the street. Actually, they spend a good amount of time sitting in traffic. So a review that takes this into account would really be more applicable for me.

Of course, if I had a test track in my backyard, things might be different...

-s-

SLK55_AMG

nice review!

miroj

So the message is that they are not a racing car. Darn.

ajoe

I currently have the AMG speedshift in an E55. Personally, I feel it works extremely well but I understand what the reviewer is refering to. It's really a matter of timing and familiarization. With a manual clutch the engagement of the lower gear is completely predictable and controlled with your clutch pedal. With the speedshift the engagement of the lower gear is controlled by the transmission and is ever so slightly less predictable and at the limit type driving taking a corner could prove disconcerting. Basically, I've found that downshifting a little bit sooner should remove this objection. As for the objection to the seven gears, well it's just silly. I've driven the slk350 and I would say this is the strongest positive to the performance of the car. I wonder what he'll say when he test drives the new M5 with seven gears and the SMG.

UStifosi

The article mentions that the trans/engine doesn't blip on downshifts. It clearly says in the new SLK sales brochure that it DOES blip on downshifts. Perhaps the writer drove a pre-production model.

MelsE55

Interesting perspective, I too have an E55 (W210) and have found the downshifts to be acceptable. It is the upshifts that I have a problem with. In mid to heavy throttle I like to torque the engine and upshift a couple of grand short of redline. The trans will not let me do that. It typically wants to take the shift to redline. Sure I can back off the throttle and get it to shift, but that is not the point is it? I love my car but I could have something a little more tiptronic like, if not a manual. A good six-speed would make the car a total blast.

SLK55_AMG

[QUOTE=miroj]So the message is that they are not a racing car. Darn.

yeah its a picking up hot girls car

SLK55AMG

The 7G SLK350 I drove recently didn't blip the revs on downshifts.

aga

I have the SLK32 AMG and I am extremely disappointed with the shifting abilities of the transmission on the track (and any other time I want to actually DRIVE). My complaints mirror what the review says. The shifting is unpredictable and, to some extent dangerous. My biggest problem is that the transmission has a large latency before the shift happens. Sure the shift happens in a nice 1/3 second, very wonderful. But the 3/4 second wait is atrocious. This makes anticipating the shift point even harder. What makes it even worse is that it appears to make the calculation as to the ability to downshift at the point you hit the shifter, but the actual shift doesn't happen until 1 second later. The net effect when you are braking hard before a corner is that it will disregard your downshift. You are going to fast to downshift when it decides, but by the time it would have actually shifted things would have been ok. So even if you can anticipate the proper shift point, the car won't let you do it. No wonder there aren't many Mercedes at the track.

Now I don't drive at the track that much, but given the design intention of the vehicle it sure as hell should be able to perform adequately. The engine and brakes function wonderfully, the car handles pretty well, but the transmission just stinks.

The last issue I have is the lame concept that when you put it into manual mode that it will still automatically shift for you. Any other car knows how to use a rev limiter, what's wrong with using that? I don't want the car to up-shift when I hit redline in the middle of the turn, that's going to kill me. They claim it's smart enough to not shift in a corner in automatic, it certainly should have been made smart enough to not shift at redline if you're in a corner.

-Alan

miroj

Wah wah wah ...... someone call a Whaaaaambulance.

F1 pace car, CLK DTM, CLK-GTR ..... all examples of Mercedes racing cars. Strangely enough all of these cars are more expensive than the humble, bottom of the ladder R171.

SLK55_AMG

hehehe

Bilal

Fear not, even though Mercedes makes probably the best autos in the world,(they're built inhouse). An auto can never be setup for track use, UNLESS its either in the SLR or CLK-DTM, those cars shift extremely quick for an auto and in manual mode are just incredible, almost like driving an SMG.

In autocar recently, AMG said 4-5 years from now there will be DSG in their cars. This means auto when you want, SMG when you wanna play. Should solve all the transmission shortcomings of this generation of AMG cars.

miroj

Well let's all hope that AMG get's its own gearbox in the future. It would be interesting to see AMG get the advances in sport performance before production cars so that at least AMG stood for something more than wheels and plastic with the odd motor change.

SLK55_AMG

yeah, good idea i guess

jco-amg

The last thing I want to have happen is to bounce of the rev limiter in the middle of a corner...it will just kill your momentum...If you are at red line you WANT the car to upshift...otherwise your dead meat.

What you do not want to have happen...and AMG has done a good job of this...is for the car to upshift in the middle of a corner while holding the throttle in sweet zone of the power band...something most autoboxes do not allow...the AMG boxes do a great job...

If you want a track car buy a REAL track car

aga

I agree that the car doesn't upshift in the corner if you are not at redline, and that is good, but of course in manual it shouldn't do that anyhow.

I don't know what your understanding of a rev limiter is, perhaps what was on my Nissan Pathfinder. It was horrible, it would KILL the engine, then restart it after the revs fell 300-500 RPM. Then you would hit it again almost before you could react. The net result was something very much like someone learning (poorly) how to drive a clutch. You're right, not good at all.

However, my Honda motorcycle, from 1991, has it figured out quite nicely. The rev limiter hits at about 300-500 RPM over redline and it simply stops the engine from accelerating, very nicely and smoothly, you almost wouldn't notice. It will just hold it there if you don't shift. This situation would be FAR preferable to the upset caused by a downshift, talk about a loss of momentum, and also a potential catastrophe in the making. Should the downshift drop to a significantly higher torque range the upset could well brake your tires lose. Something that certainly wouldn't happen by just holding the car steady.

So, no I do NOT want the car to upshift, and I can't imagine anyone who has actually driven at the track who would. The evidence of this is pretty obvious when you look at any of the more track oriented cars. They will not shift unless you tell them to. I have heard that you can even go quite overboard on the Ferrari and actually harm your engine, but they will let you do it.

SLK55_AMG

actually, redline on a corner is the best, even in a manual i used to downshift in a corner , more torque is needed in a corner... who goes racing here?

upshifting in a corner just makes the car slower and more tending to make an accident + you lose control (road holding) some people really need racing lessons...

SLK55AMG

I do trackdays quite a lot...... and not quite sure what you are saying.

The best way to take a corner is to be in the correct gear BEFORE you enter the turn. If you (or the car) change gear up or down during the turn it will unbalance everything and risk spinning out. The only corners that should involve a gear change are those long sweeping bends where you max out in one gear and need to change up.

When you say "redline on a corner is best" I assume you mean hitting the redline after the corner is best? As you say you need peak torque when powering out of a bend and this is almost never anyway near the redline (peak torque is usually a few thousand RPM below the redline)..... so when going into a corner you need to select the gear which will give you good torque on the exit that won't also run out of revs mid turn.

SLK55_AMG

You are the man, dude!


i bet you are a great driver