Optimum Fuel Consumption

[ITSACLK320]

Does anybody know what speed gives the optimum consumption for a CLK 320 (2000 model)

PS. Im not sure if this is a daft/unanswerable question!!

Cheers

 

[Blobcat]

Stopped (with the engine off) ;-)

Failing that constant 56mph always used to be the highest mpg figure quoted. I remember reading somewhere that you use 25% more fuel travelling at 80 than 60

 

[alec2]

The engine will be at it's most efficient when developing maximum "Brake mean effective pressure" which occurs near the peak of the torque curve.

But this does not take into consideration the effects of friction and air resistance.

So when accelerating I would keep revs near the peak of the torque curve( That is what your gears are for!)

And when crusing keep the speed down.

On my c class 220 CDI The mpg is very much better if I cruise at 60 rather than 70

Turn off the A?C if you want to save fuel.

Alec

 

[television]

Stopped (with the engine off) ;-)

Failing that constant 56mph always used to be the highest mpg figure quoted. I remember reading somewhere that you use 25% more fuel travelling at 80 than 60

Spot on, My V70 R will do 50mpg at 55mph, around town 21mpg,at 70mph 30mph at 80mph 25mpg

This is though a turbo engine

My SL 320 would do 33 mpg at 75mph I never drove that at 55mph

 

[A210AMG]

Hello,


So in my ML, if I fold the mirrors in turn the A/C off, pump the tyres up and cruise at 56mph I may see 30 out of it

 

[Braveheart]

Hello,


So in my ML, if I fold the mirrors in turn the A/C off, pump the tyres up and cruise at 56mph I may see 30 out of it

You forgot to mention, choosing a dry still day, with no head wind, and roads with a good surface, and don't go over any cats eyes.....and be careful of HGV slipstream....

 

[jberks]

The best trick I found on modern motorways and roads are to give as much as a gap as you can get away with, anticipate further ahead (don't much care what the guy in front is doing, it's the one 4 cars up that I watch) and try to coast when the inevitable slow down comes. It's a great game, try to avoid braking at all. Often you get down to 30mph or so and the traffic sudenly tears off again. Any coasting is effectively free motoring.
I always think of the brake pedal as a money burner and only use it if it's going to be more expensive (and painful) not to!

 

[psmart]

Stopped (with the engine off) ;-)

.... Miles Per Gallon ... Gallon = 0, Miles = 0! best option if you cant get the wife to push is pull the ECU plug out and call the AA, can got from Lands End to John O'Groats sat on the back of a low loader in your comfy Merc for 0 gallons

So in my ML, if I fold the mirrors in turn the A/C off, pump the tyres up and cruise at 56mph I may see 30 out of it

Andy Wr and U are definitely doing something wrong if you cant get 30mpg ... last time I checked I was getting 28 driving back and forth to Menwith hill which is up and down yonder hills... not the best conditions!

Best mpg is as per JBerks, driving style but also turn off things you dont need running! In Austria they have a law where you have to have the lights turned on whenever your driving, which can be anywhere from 20-55 or more Watts per hour consumption. Not much for short journeys, but when you take the lower figure and multiply it up for the average number of cars in a 24 hour period using their roads, it works out at 20 x 2 = 40W/h x 24 = 970W/h per day x 1,000,000 (average number of vehicles in motion everyday) = 960,000kW/h. If you then start working out the efficiency of the alternator and engine, its astronomical in terms of fuel!

 

[wireman]

Best speed is around 50-60 dependent on how good the CD is, aerodynamic resistance follows cube law so it takes 8 times the power to travel twice as fast. At 55 or so the wind resistance is just starting to become significant, below that friction in tyres and driveline are significant, IC engine efficiency is abismal at low power outputs.

 

[GGB]

To Hull and Back!

I've had to take my '99 C220 CDI to HUll and back a few times for work recently and I was most chuffed to get 560 miles from 1 tank! I wasn't hanging about either (mostly 80ish).