MachtigAvant (v3.0)

Sitting here reading the latest edition of MT, and at the end of the mag they have a compilation of their road test data. I went ahead and put the MT and R&T info together. It seems that they have no problem driving the hell out of the m3. But they can't seem to handle the S4, or punch the automatic in the C32. :-? Thought it was interesting...
(Also, Car and Driver got a 4.9 0-60 for the S4)

Audi S4: 340HP
Motor Trend:
0-60= 5.0s
1/4 = 13.4/105.1 MPH

Road and Track:
0-60=5.4s
1/4 = 13.9/101.2 MPH

BMW M3: 333HP
Motor Trend:
0-60= 4.7s
1/4 = 13.2/106.9 MPH

Road and Track:
0-60 = 4.7s
1/4 = 13.3/106.8 MPH

Mercedes C32: 349HP
Motor Trend:
0-60= 4.8s
1/4 = 13.2/106.9 MPH

Road and Track:
0-60= 5.1s
1/4 = 13.6/105.4 MPH

Ram@S4-MTM

Yeah - and we get 320ft lbs from an S4 when Audi say 302ft lbs - what's the world coming to!

Sia Bani

based on the results I've had against stage 2 b5, etc.

MachtigAvant (v3.0)

I know, did we ever figure that one out?

quickersilver

...a few of these cars seem to be down, or up, on horsepower.

Slightly more complicated answer:

There is a very accurate equation which allows you to calculate a car's horsepower if you know its weight (with driver, referred to as "as-tested" weight) and trap speed in the 1/4 mile. This was in Road & Track's tech section some time back. I took it, tried it using a dozen or so cars' test results, and found it to be very, very accurate. I've provided a link below to a calculator which uses it; give it a try! The ET one doesn't work as well, so use the "calculate using MPH" button...

Anyway, the equation is:
hp = w*(spd/234)^3
where
hp = crank hp
w = weight of car with driver
spd = trap speed in 1/4 mi.

So, if we look at the two M3's speeds you gave, which are very close (say, 106.85 and split the difference), using curb weight of 3450 + 180 pounds for driver & test equip:

hp=3630(106.85/234)^3 = 346 horsepower. A bit higher than the car's rated 333...

As to the S4:
Motor Trend's article gives its weight as 3825. Adding 180 pounds for driver/equip, we get
hp = 4005(105.1/234)^3 = 363 horsepower. Also a bit higher than the car's rated horsepower...

Conversely, Road & Track's S4 was about 80 pounds heavier...its weight was 3900 pounds, as-tested was 4080, sooo..
hp = 4080(101.2/234)^3 = 330 horsepower. Pretty close to rated...

The C32 Motor Trend tested weighed 3540, giving
hp = 3720(106.9/234)^3 = 354.7 horsepower.

Finally, Road & Track's C32, which had an as-tested weight of 3830:
hp = 3830(105.4/234)^3 = 350 horsepower.

Mainly seems to be weight differences and horsepower differences among cars. And of course, test surface/temperature will play a part, especially with the lower-traction RWD cars.<ul><li><a href="http://www.streetrodstuff.com/Tech_Stuff/Horsepower_Calculator.php">Horsepower calculator; use weight of car w/driver (</a></li></ul>

MachtigAvant (v3.0)

That's great info...thanks! I guess they must have had too many donuts that morning. :-D

quickersilver

"Our test driver, Homer Simpson..." :-)

MachtigAvant (v3.0)

"HMmmmmmm.......dooonuts...."

air-cooledJBJ

..over the years. But not just with the M3, S4, and C43/C32 comparisons, with many sports cars. I've been reading Motor Trend, which is my favorite, since I was about seven and I've been reading Road &amp; Track for about two years now. There's always a discrepency with the acceleration figures between the two mags. In fact, it's between C &amp; D and several other mags too.

Maybe MT drivers are better drivers? They're paid by BMW? Leaning towards the latter judging by some of the cars MT has chosen for it's esteemed "car/truck of the year". Maybe both?

I choose to believe MT's figures though (loyalty?)

MachtigAvant (v3.0)

Since the S4 won... ;-D