SLcharger

Have any of you ever given it a thought why the SL 55 AMG has a better fuel economy than the SL 600 ?

To my opinion it schould be the other way arround.

MB official numbers:

SL55AMG City 14 mpg Highway 20 mpg.
SL 600 City 13 mpg Highway 19 mpg.

Any surgestions ?

Chris 45971

I'm not sure, but don't the extra cylinders require more fuel (8 to 12)?

vraa

Who cares, the EPA tests are crappy like none other.

http://www.ucsusa.org/clean_vehicles...omy-tests.html

SLcharger

You could both be right and wrong.

It could be interesting to get some figures from the real life.

How is fueleconomy on YOUR SL ?

Chris 45971

19.5 MPG over the last 7000 miles in my 500.

JackStraw

On a long highway trip, I average 22 mpg in my 600. In mixed city-highway medium distance trips I average mid-teens. City only driving yields sub 10 mpg.

E55AMG99

Many factors such as
Weight of each car
Displacement (not # of cyls)
Efficiency (how much fuel is required to make one HP)
Gearing
torque vs. RPM (car with more low end will make more EPA MPG)

WIldcat465

That's about what I get in my 600. My CL500 get mid 20s on the freeway and high teens around town.

acicchelli

I get around 12 on my SL600, I cant keep my foot off the pedal.

SLcharger

I make a decent average of 15 mpg in my SL55, and I do like to feel the chill down my back when I let the hammer fall. The sound is incredible.

The figures from the SL 600, clearly shows that the fuel consumpsion is higher than my SL55. It would have been nice with some more feedback from other SL55 owners, but as that is not so, my figures will have to do.

My point is:

The SL 600 has turbochargers, who get their energy from the free energy in the exhaust gases. No energydraw from the engine, thats what makes the turbocharger so unik.

The SL55 has a supercharger ( S/C ) and this S/C takes around 100 BHP from the engines crankshaft ( at full load ). By doing that it produces arround 170 BHP extra, that will crank out on the flywheel. We have a loss of 100 BHP.

It can only be that the V8 S/C has a mutch better fuel efficiency than the V12 Biturbo engine.

Could it be that SL55, at last, have one advantage over the SL600 ?

Comments invited.

WIldcat465

You can have your efficiency.

I'll keep my gas guzzling 600.

SLcharger

Take it as a man, you cant win every time.

We only have the fun we make up, right.

I think the SL 600 is a great car, and if I had to choose a second MB, that would be it.

Have a nice day.

doltmo

The supercharger on the SL55 engine runs only when you (a) put your foot in it, or (b) anytime the RPM is above 2750. So if you cruise under 88 MPH, you don't lose horsepower to the kompressor. You're left with an SL500 engine with:
1. lower compression: 9:1 vs 10:1 (lower volumetric efficiency),
2. 10% more displacement and a longer stroke (more internal friction loses?),
3. higher engine RPM at a given cruise speed. 7th gear in the 7-speed is 0.73:1 vs. the 0.83:1 5th gear in the 5-speed. At 80 MPH, the SL500 turns 2190 RPM, the SL55 runs 2497 RPM, assuming factory tires.
4. 200 more pounds of weight (steel vs. aluminum front and rear subframes) to drag up the hills, and
5. the AMG body skirts increase aerodynamic drag (ironic huh?).

The 600 comes with a 2.65 rear end, so it cruises at a slightly lower engine RPM (2346RPM at 80 MPH) than the SL55, but still much faster than the SL500. And I would guess that with all those cylinders there's more internal friction. Plus there's another 200 pounds on top of the SL55.

I got 25-26mpg on the SL500 consistently on the highway, with a tops of 28 to 28.5 if driven very carefully. The instrument cluster mpg display was about 0.7 mpg conservative.

My SL55 can get above 20 (my best was 22.5) if you go easy on the gas - but it what's the point?. The difference between a 25 MPG car and a 15 MPG car is less than 7 cents per mile at today's gas prices.

shoes

I have owned both and consistently averaged 17 miles per gallon in both.

sillydriver

Same here -- I've owned both and averaged between 16 and 17 in both.

Auraraptor

I get 5.5 city and 17.4 highway, stock 600.