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Premium Member 2012 SLK55 AMG
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Discussion Starter #1 (Edited)
A few people on the forum @JockySteer and @davest4s to name a couple have asked me for my thoughts on the R172 SLK55 AMG. I've deliberately waited a while to post so I could really get a feel for the car and give a decent appraisal of it's strengths, weaknesses and generally how I'd compare it to the R171 SLK55.

The Exterior

The look of the car divides people as we all know. Many can't stand the new squared off front end particularly when compared with F1/SLR inspired lines of the R171. For me I found that the shape had grown on me before I bought one and it has continued to do so since I took ownership. Don't get me wrong I still love the R171 shape but I think the R172 definitely has a more masculine look than it's predecessor which I now prefer. Like the R171 if the R172 has a bad viewing angle I'd say it's the square on front view but from every other angle I personally think it looks great. My favourite part of the body styling would probably be the rear quarter panels, I love how they are shaped.

I'm not a big fan of chrome and had to tame down the front grille, there was just too much of it in that area for my liking. I also hated the cheap looking plastic bonnet vents. Ironically I think these need the chrome fins to be in keeping with rest of the car. The vents can be made to look better in a number of ways but I opted to paint them flat black before fitting the fins. I also did the same with the rear diffuser to take away the grey plastic look.

The Interior

The cabin in the R172 is a very nice place to be! The seats are a big improvement over the R171 and the all in all the trim just looks and feels more premium. I was never a fan of the black rubber used extensively in my R171. To cut a long story short the interior trim is a massive improvement over the R171. The controls and infotainment system are generally good but in my car I don't have the Harman Kardon speaker upgrade which I had in R171 and therefore the audio quality isn't as good.

Performance/Driving

Despite the obvious similarities between the two cars there are a number of differences which I think really stand out. The ride quality is far superior in the R172 and handling seems to have improved considerably too. The R172 feels lighter at the front and seems to turn in better and with less body roll than my R171. Granted the mileage difference and condition of the suspension may have a bearing on this sensation but I believe the R172 is far less prone to understeer. The better ride quality and improved handling kind of make the R172 a little less exciting and less challenging to drive than the R171 at times. The R171 feels more of a raw sports car than the R172 but the latter is definitely more capable at the same time. It took me a long time to settle with the new car and I only really bonded properly with it on our recent trip to the Lake District. Another striking difference between the 2 cars is the exhaust note. The revised exhaust system with flaps appears to have been born out of the need to make the car sound ok when running in ECO 4 cylinder mode. It has made the car a fair bit quieter the R171. The R172 exhaust note although quieter is pleasingly deep and powerful sounding whilst remaining pretty subtle. Having replaced secondary cats/resonator with an x-pipe on my R171 I was very pleased with the soundtrack and it is one of the things I will miss! The new exhaust isn't all that bad however and I really like the 'bark' from it when rapidly accelerating and going up through the gears. The rev matching thottle blips on downshift make some sweet music too. When I got my R172 it had a defective exhaust flap on one side which was permanently closed. The flap actuators seem to be prone to failure and it's something I would urge any prospective buyer to check for before buying especially if the car is out of warranty. Driving in manual is much improved over the R171 with a much faster change using the paddles. Night driving in either car is generally very good with the bi-xenon headlights but there is a noticeable improvement in the R172 units with 'intelligence'.

Economy

Fuel economy has improved greatly with the cylinder deactivation and start stop system. I have managed 30mpg on a run. This was one of my key drivers for moving over to the R172. I think I could get great economy from the car if I could resist the urge to plant my right foot a little more but that is proving quite difficult! :wink:

Conclusion

I'm happy that the R172 SLK55 is in my view a much improved car overall when compared with the R171. I have now agreed sale of my R171, I will miss her and her soundtrack but I'm continuing to fall in love with my new ride and have no regrets about making the change. As much as the two cars are similar they are very different animals in a lot of respects too. Both are guaranteed to put a smile on your face! :smile:


If anyone is considering changing and wants to ask me a question about anything more specific I'll do my best to answer, so fire away!
 

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Thanks for that Col very interesting.

I agree with your comments on the looks, they are growing on me too.
 

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Hi Col,
I can definitely echo your evaluation, but coming from a couple of track days understeer is the one you will feel pushing to extremes. Only a real push of the pedal will change it into oversteer but since the rears will start spinning ESP will take over. Even when switched off there is still some kind of limit that cannot be passed. The system will start braking and there is no more sideways floating.


I've found that taking premium on board makes a big difference in how smooth the engine will pick up and if the start-stop system will jerk when waiting for a traffic light or so. Euro95 will run, but isn't the best.


I also find that there is no huge difference between the sports mode and the regular mode. You can't make the car 'stick' in sports mode. Every time the engine is killed it will come back in C. The main thing that happens in sport mode is a thousand RPM above what you are normally doing and going up in gears will go to redline. If there is anything else, I've must have missed it.


Brakes are great but it's really difficult to tell when ABS will take over. The optimal braking is just before ABS steps in but finding the spot is just trial and error. You can't tell by the amount of pressure on the pedal because different speeds require different kinds of pressure (I tried going from 100 km/h every time again).


Another point worth mentioning: there is a very limited offer on goodies for the 55 out there. If someone would like to dress it up the R172 would not be your choice, there is more for the R171. (and both are out of production)


A worry for me is the engine. The M152 was made for the SLK only. Very limited numbers are sold of this car (there are 20 in NL, mostly imports from Germany). What this will mean in say 10 years in parts is anybody's guess. And no, it's nog the same engine just without turbo from the C63 etc.


All this aside, I like the car. It has almost 100K km on it now and it will probably stay for a while.
 

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Premium Member 2012 SLK55 AMG
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Discussion Starter #4 (Edited)
Brakes are great but it's really difficult to tell when ABS will take over. The optimal braking is just before ABS steps in but finding the spot is just trial and error. You can't tell by the amount of pressure on the pedal because different speeds require different kinds of pressure (I tried going from 100 km/h every time again).

Another point worth mentioning: there is a very limited offer on goodies for the 55 out there. If someone would like to dress it up the R172 would not be your choice, there is more for the R171. (and both are out of production)

A worry for me is the engine. The M152 was made for the SLK only. Very limited numbers are sold of this car (there are 20 in NL, mostly imports from Germany). What this will mean in say 10 years in parts is anybody's guess. And no, it's nog the same engine just without turbo from the C63 etc.
I completely forgot to mention the brakes in my comments. That was something I worried wouldn't be as good as the those on R171. Much to by surprise they seem equally as capable but maybe lack the progressiveness in feel compared to the setup on my old 55. I have to remember to be gentle with them because the bite is very strong and instant.

Good points also about the lack of aftermarket parts compared to the 171 and also the fact that the M152 is unique to the SLK. The latter something which initially attracted me to the car but I had not considered what that might mean in the future with regards to price and availability of parts. I'll try not to lose any sleep over that one for now. I'm just hoping the M152 proves to be as reliable as the M113 obviously is. :smile:
 

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Great write up Col, although I only owned a 350 with the AMG package previously the difference is night and day when it comes to how the two cars handle; and the interior is far superior. The stop / start drives me nuts and I turn it off as soon as I get in the car, only because I nearly got myself killed making a left turn:surprise: stationary in the middle of the road I thought I'd nip in the gap between the oncoming traffic to make the turn as I would normally do (if you drove here you have little options unless you want to sit in the middle of the road all day) and forgot the engine had turned off. Shoving my foot on the gas pedal to make the turn only started the engine and I was committed to the turn. It was slow pulling away. To say it was a close shave would be an understatement, from that day forth as soon as I start the car the 'eco' button gets turned off except if I am going on a long highway cruise.

I think if MB could rewrite the software to ensure the start/stop is disengaged when a turn signal is activated they would be on a winner, but it's bloody dangerous as is IMO.

Like you I was apprehensive about the styling, if that's what we should call it...I called it the ugly family member that you become to love:laugh: As you so rightly pointed out, depending where you stand to look at the car it can be ugly or good looking. If the entire car was lowered and widened it would be awesome. And as for obtaining after market parts, well they are a scarcity. I have been trying for months to find some rims..no joy so far. Although you can buy wheels with the right bolt pattern and bore size the offset is never right; I won't use spacers etc as I had a bad experience in a previous vehicle. I have having the calipers painted tomorrow and some partial wraps done the following week. I am trying to find some black gloss wheels, failing which I will have to have my current wheels refinished. The cheapest I can find a set of OEM black is $800US per wheel, which will work out $1000 Cdn by the time you add shipping etc....I have tried a few scrap yards in case someone has had a death in the family but alas the 55 is so rare around these parts I think they stay in the garage:frown:

As I have a company car I never intended to drive it to work....but with the great weather we have had the company car stays in the garage while I rack up the miles in the mini beast>:D
 

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Hi Col,

Thanks for the review. I am curious if you noticed the difference in acceleration of the R172 compared to your R171?

Bob
 

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Registered 2013 SLK55 AMG
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What a great read, thanks to all for taking the time to record your thoughts...

Having only had my 55 a week I am still getting to know the finer detail of ownership, the excitement of driving and the enjoyment of the sound tack every time you depress the loud pedal!

However I can already relate to many of the points above and find it refreshing that some of the points I have already noticed are not just me being slightly critical of a new car...
 

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Premium Member 2012 SLK55 AMG
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Discussion Starter #8
I've not had many issues with the start stop but I do turn it off a fair bit when it gets annoying! I had one occurrence of ECO mode not functioning at all and not being available until the next time I started the car which was strange and the start stop function seems a little unpredictable at times.

Acceleration wise I believe that the difference is noticeable! I noticed the difference in real time during some spirited driving along with R171 55s in the Lake District and the Yorkshire Dales. I was able to pull away and open a gap when leading and found closing the gap when chasing was easy too. It would be interesting to see what the difference would be over a quarter of mile from standing start.
 

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I've not had many issues with the start stop but I do turn it off a fair bit when it gets annoying! I had one occurrence of ECO mode not functioning at all and not being available until the next time I started the car which was strange and the start stop function seems a little unpredictable at times.

Acceleration wise I believe that the difference is noticeable! I noticed the difference in real time during some spirited driving along with R171 55s in the Lake District and the Yorkshire Dales. I was able to pull away and open a gap when leading and found closing the gap when chasing was easy too. It would be interesting to see what the difference would be over a quarter of mile from standing start.
Star stop has a mind of its own and it switches off at some random times. Great review, I managed 34.4 mpg today, absolutely insane. At the same time on some country roads the car absolutely flies and sounds crazy with the xpipe and flaps open.

Way more planted than the R171, that car never felt all that secure on the road...that said, the R171 gave much more feel on the road. The brakes were also better, but it couldn't get the power down anywhere nearly as well.
 

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Way more planted than the R171, that car never felt all that secure on the road...that said, the R171 gave much more feel on the road. The brakes were also better, but it couldn't get the power down anywhere nearly as well.

Uh, better brakes? Are you comparing the same systems? I mean P30 package on both? The P30 front brakes on the R172 are pretty amazing in my book.
 

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Premium Member 2006 SLK55 AMG
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Great review Col, I am looking for an r171 but would love even more to own a r172. Slightly out of the budget at this point though!
 

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Premium Member 2012 SLK55 AMG
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Discussion Starter #12
Uh, better brakes? Are you comparing the same systems? I mean P30 package on both? The P30 front brakes on the R172 are pretty amazing in my book.
My car in non P30 and find the brakes are great! What are the differences brakes wise on P30. Are the other goodies the active suspension and unlimited top speed?
 

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Premium Member 2008 SLK55 AMG
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Great reviews, i've been trying to find comparisons for a while. My R171 is way fast enough, but gearchanges using the paddles, seem very slow. I am used to bikes, that SEEM a lot faster, but only being 2 feet wide, are just easier to go fast everywhere without thinking about it. I'm still struggling to get used to the change. But fuel consumption, is better than my wildest dreams. I was expecting 16-22 MPG if i was lucky. I have just done a 1700 mile round trip to Scotland, and averaged 27.4mpg. The last days return from Edinburgh, was 28.5mpg (430miles). The advertising i've seen for the R172 says up to 30% better than the 171 !!! So what is the best you've seen ? 37 anybody ?
 

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Great reviews, i've been trying to find comparisons for a while. My R171 is way fast enough, but gearchanges using the paddles, seem very slow. I am used to bikes, that SEEM a lot faster, but only being 2 feet wide, are just easier to go fast everywhere without thinking about it. I'm still struggling to get used to the change. But fuel consumption, is better than my wildest dreams. I was expecting 16-22 MPG if i was lucky. I have just done a 1700 mile round trip to Scotland, and averaged 27.4mpg. The last days return from Edinburgh, was 28.5mpg (430miles). The advertising i've seen for the R172 says up to 30% better than the 171 !!! So what is the best you've seen ? 37 anybody ?
Not wishing to "hi jack" thread but while fuel consumption is being mentioned, I thought I'd just post this for information purposes...
Last time I went to Southampton UK driving around 70 MPH on dual carriageway...
 

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My car in non P30 and find the brakes are great! What are the differences brakes wise on P30. Are the other goodies the active suspension and unlimited top speed?
P30 = LSD in the rear, Ceramic brakes on the front, 280 top speed, AMG driver experience course, other dampers all around. Not the auto adjust type.


I had the speed limit removed when I had my tune. There is a theoretical top of about 305 km/h now. Never had the nerve to push it that far yet. All I know is that @250 there was still acceleration available (to 280 at that time).


Mind you, I have a tune and BMC filters on board. MBH long tube headers were on my list but I'm hesitant about them because of the noise.
 

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...assuming you're using "imperial gallon" = 1.2 x "U.S. gallon", that's ~34 mpg for the folks on our side of the pond.
Well I you are converting the 29.7 mpg in the picture and it is based on the imperial gallon then the US equivalent will be about 24.75 mpg. "Bigger gallon" equals more mpg.
 

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Acceleration wise I believe that the difference is noticeable! I noticed the difference in real time during some spirited driving along with R171 55s in the Lake District and the Yorkshire Dales. I was able to pull away and open a gap when leading and found closing the gap when chasing was easy too. It would be interesting to see what the difference would be over a quarter of mile from standing start.
Car & Driver 2005 SLK55
0-60 = 4.3 sec
¼ mile = 12.7 sec @ 111 mph

Car & Driver 2012 SLK55
0-60 = 4.1 sec
¼ mile = 12.5 sec @ 116

Although the above acceleration times were done by the same magazine there is no listing of temperature or altitude recorded so the times may not be comparable.

At 60 mph that 0.2 sec is about 17 ft. or about 1.3 car lengths.
At the end of the quarter mile that 0.2 sec is about 34 ft. about 2.5 car lengths.
 

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Well I you are converting the 29.7 mpg in the picture and it is based on the imperial gallon then the US equivalent will be about 24.75 mpg. "Bigger gallon" equals more mpg.
Doh! Didn't open the thumbnail and locked on the "41" as the mpg. ...someday I'll learn.
 

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Registered 2013 SLK 55 AMG
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Great thread and as an owner of an R172 55, an interesting insight into the previous model. We drove 2 cars before buying our PP-equipped model - one R171 (briefly) and a non-PP R172. The main difference for me between 171 and 172 was the step change in the gearbox control software, as the speed of change in Sport or Manual when using high load, large throttle was significant. I love the way the 172s 'fart' on the way up and execute perfect, quick 'blips' on the way down, very nice. And that the instrument panel flashes RED as you approach the redline in Manual is icing on the cake.


The non-PP 172 was too soft for me in truth, although if you are annoyed by the state of the UK roads I'd understand why you'd prefer the softer setup. But for me I like the additional control at higher speed of the PP setup. That it brings the LSD, 'compound' brakes (silly name for separate Bell/Disc brake setup) and tasty steering wheel with it as well, all adds to the pleasure. And of course the R172 allows the TC/ESP to be completely switched off....


We had a trip to Munich last year and it easily hit an indicated 160-170mph whenever the traffic cleared and over the trips 1700 miles averaged 28.7mpg, with a best day showing 34.4mpg whilst on a nice 60-80mph cruise. Quite some car.


And it's a keeper for now, as it is the last ever normally aspirated AMG engine, has proper hydraulic power steering and revs to 7000rpm. If ever there were grounds for future values holding firm or maybe rising, then this is it I think 0:)
 
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