I haven't looked at the mags lately but I don't understand how these numbers add up.

It seems people are saying both vehicles are within .5 sec in the 1/4 mile. Also, that the M5 would begin to pull away at higher speeds due to its higher HP. Then, the comment is made that the M5 hits 100 up to 1 second faster than the SLK55. If that is the case, it should smoke the SLK55 in the 1/4 mile.

Please explain. I doesn't make sense to me.

 

Mags will conflict with eachother due to different conditions. I don't think an M5 is going to pull a full second up to 100 mph on an SLK55. That is a HUGE difference & makes no sense whatsoever. The SLK will do well (likely deadlocked w/the M5 due to its gearing) up to ~ 90ish but will then start getting slowly pulled (evidenced by the M5's higher traps). Now, if the M5 is carrying 4 - 5 people, the SLK might stick with the M5 or even pull it (extra weight & no more torque than the SLK to pull the extra heft).

Some guy was in a new silver M5 this weekend & saw my RX-7 in his rear view getting onto a freeway. It was dangerous merging (hardly any room due to the short entry & exit Hwy ramps) so I left him alone (but he thought he was "Fangio" & floored it at the slightest opening in traffic). Traffic cleared later & I walked him on a 70 mph roll. He drove past & just looked at me with big eyes when I was exiting. I don't think he was expecting to get pulled like that upstairs. Pesky rotaries.

-Matt

 

DSB:

To answer your question in two words...torque and horsepower (three words if you include the conjunction). The SLK55 has a huge amount of torque (376 lbs-ft) for such a relatively light vehicle (roughly 3,400). In fact, it nearly has as much torque as the E60 M5 (383 lbs-ft) However, the M5 weighs in at over 4,000lbs. The relative torque advantage allows the SLK55 to propel off the line much faster than the M5. This gives the SLK55 such a distance advantage that the M5 has to fight the pretty much the whole length of the 1/4 mile to edge (or barely not edge) the SLK55 (depending on who you ask). The M5 has the ability to gain as the speed increases due to the much higher horsepower.

Tom

 

I don't really agree with that analysis. M5 can get off the line just as quick as SLK55, both cars have been tested at low 4 seconds to 60 by numerous automobile magazines. Look at the 0-60mph time for an M5 from R@T a couple of posts above, its 4.1 seconds! So how is the SLK55 much faster off the line... show me some data that supports this because the best 0-60 time for an SLK55 I found was 4.3 by car and driver. If properly launched, the cars will be fairly even at 60mph and M5 will start to pull away. M5 will get to 100mph around 0.5-1.0 seconds quicker than SLK55 and will just continue gaining speed until it gets through the 1/4 in mid 12's (again, see R&T article, it achieved 12.4). So in summary:

0-60: Very close, M5 slightly faster is properly launches. M5 best is 4.1, SLK55 best is 4.3. In either case, 0-60 is pretty dead even.

0-100: Unquestionable, M5 is much faster to 100 by as much as 1 second. By 120mph, the gap is only larger.. SLK55 will be several car lenghs behind at this point.

1/4 mile: M5 is faster at mid 12 to SLK's high 12's. M5 is also traveling a good 5-8mph faster than SLK55 at this point.

Of course my analysis assumes both cars were driven to their fullest potential.

 

Actually, the best recorded for the SLK was 4.2... but can't remember where it was done.

The SLK gets 4.3 seconds on many tests. Numerous car magazines have shown this number, and members that have drag raced theirs confirmed it.

However, whilst the M5 has received one instance of 4.1 seconds, from my personal observations, the average number is closer to 4.5...

But so many things come into play that I don't take it all too seriously. A tenth of a second here or there... pfff... it could very well be that I'll lose that tenth of a second in any street race (which I don't do btw) by a moments inattention or having a few thousand miles too much on my tires, or simply hammering the throttle too hard.

 

Tuskir:

Let's set the R&T test of the M5 aside because I have no direct R&T test of the SLK55 to compare to it. That also is a moot point, as in that test the M5 would be ahead pretty much the whole race (it really hooked up right off the line). Lets Look at the Motor Trend tests of the M5 (let's use the "worst" test just to illustrate my point) and the SLK55:

M5 / SLK55
0-30: 2.0 1.7
0-40: 2.7 2.4
0-50: 3.7 3.3
0-60: 4.5 4.5
0-70: 5.7 5.7
0-80: 7.0 7.3
0-90: 8.4 9.0
0-100: 10.0 11.0
1/4: 12.9 12.8
speed: 114.9 109.2

The only explanation for the 1/4 mile results is that the SLK55 gets a huge distance lead from 50 mph and below. That lead was established by the relative torque advantage of the SLK55. I am not sure what the gearing in each gear is on the SLK55 is compared to the M5 (the SLK55 has an axle ratio of 3.06 and the M5 has a 3.62, but you would need to know the ratios of each gear to figure the torque multiplication). That would also be a torque factor.

Tom

 

Tuskir:

BTW... I am in agreement with you (as I previously posted) that the M5, driven to its fullest is faster than the SLK55 given the same circumstances. But I also agree with Yellow R1, that given the average driver and average conditions (and not from a highway roll) the SLK55 could "upset" the M5.

Tom

 

SLK55 gear ratios:

The full C/D article can be found at Car and Driver SLK55 Road Test

 

Interesting, that the SLK55 is in 4th gear at the end of the 1/4 mile and getting ready to shift into 5th gear (114mph at 4th gear redline). Meanwhile, the M5 (which also has 7 gears) is in the middle of its 4th gear while its crossing the 1/4 mile traps. It won't hit its 4th gear redline until 126mph.

Also, I forgot to address where each car's torque characteristics lie. The SLK55's peak torque at 4,000 rpm. The SLK55 is pretty much hitting its sweet spot right at launch. The M5's torque peak is extremely high at 6,100 rpm. The M5 would not be using its maximum grunt until it is well on its way. I don't think the SMG will readily allow the M5 to drastically rev the engine on launch. This could explain that the gearing is actually favoring the M5, but the lack of low end torque and extra weight can not be easily overcome. This could also explain Road & Track's really good results. The M5 had a 1.7 sec 0-30 time which is almost unheard for a non-AWD car its size. They may have launched the M5 in an almost abusive way that most owners/testers would not.

Tom

 

Thanks for the data and explanation you guys. I guess it does make sense. I would love to run against an M5 some day. I wonder what real world results would be. Like many said, it probably would benefit the SLK driver and the end result would probably be much closer than any magazine... at least off the line and not on a roll.

 

For the record, E60 M5 is mostly SMG (with MT introduced only this year) with launch mode.. It really doesn't take much driver skills to do a good launch in one of them...

 

no launch control for the US! I dont know how many M5 drivers drive around in M dynamic mode all the time. The car is so overly configurable that when push comes to show you are likely in the wrong gear ferocity or you forgot to ask the car for the extra 100hp.

Having driven one that a dealer in my area had (out of break in with the full 500hp).....the steering is wonderful for a sedan car and is almost direct like a porsche. The SMG is great when you are determined to use it and head up dispay is a must to see what gear you are in (as unlike a manual, you cant just reach down and feel the gear). Downshifting with the rev maches is awesome.

Having said all this is traffic and daily non murder mode of driving, this car is an absolute pain as a manual. It is lurchy and sometimes it dosent downshift when you want it to (you have to ask twice!!!!). In auto mode which it again has 4 or 5 settings for it is just horrible. The shifts are just lazy.

Anywho, my initial query was just to see how this car compared to the SLK55. I have been thinking about getting a M5, 6 or a 997 S in the future. I just wanted to see if there were any opinions to sway me toward the M.

Since I have a SLK55, your opinions are likely to me more justifiable to me that any from a BMW M forum. Besides, M drivers think that their cars are better than anything out there.

 

Isn't that the truth, reminds me of honda drivers, "When VTEC kicks in it's OVER!" but their slogan is off by much, "When VANOS kicks in it's over" But I still have alot of respect for M3's, they are affortable and fun. New one looks boring, BMW went cheap on this one, the exterior looks like a 335i with a different front spoiler and quad tips. But can't complain about 400hp V8.

 

Or we could look at the C&D results: (in quick search couldn't find full data on '06 M5 SMG):

M5 / .......................SLK55
0-30: 2.0................ 1.7 -> 1.6
0-40: 2.7 .................2.4 -> 2.3
0-50: 3.7 .................3.3 -> 3.2
0-60: 4.5 -> 4.2 .......4.5 -> 4.3
0-70: 5.7 ................5.7 -> 5.4
0-80: 7.0 ................7.3 -> 7.0
0-90: 8.4 ................9.0 -> 8.5
0-100: 10.0 ...........11.0 -> 10.3
0-110: .............................12.6
0-120: .............................15.3
1/4: 12.9 ->12.5 .....12.8 -> 12.7
speed: 114.9->118 ..109.2-> 111


Of course that is with the M5 SMG in Optimal mode, if you caught him just daily driving, he might be normal, and then the SLK is really all over him.

Now, interesting look at C&D data on the 2007 M5 with manual trans.

M5 lost 0.5 seconds in the 0-60: 4.7

and the 0-100 is 10.3

with the 1/4 at 13.0 and 114sec

They attribute that NOT to their skill (or lack ) but due to the M5 engine really being better matched to the SMG 7 gears than the manual 6 gears.

So I think the SLK55 still stands a good chance on "average"!

And to top it off, for your extra $20K you lose the glorious hardtop convert!

 

bloflin:

If I recall the test of the M5 manual version correctly, they complained that the car could not be launched easily because of the traction control kicking in. Apparently, BMW in their infinite wisdom (being facetious) decided that American drivers would get into too much trouble if the traction control was able to be fully disabled. I find it pretty pathetic that my old 400hp E39 M5 was tested in C&D to the same 0-60 time as the new 500+hp.

Tom