Optimum Speed for Optimum MPG? SL350 R230 2004

[zentrex]

HI, Given we are all facing high fuel costs I wondered if anybody had done a break down what is the Optimum Speed for Optimum MPG? driving an SL350 R230 model?

Obviously it is affected by driving style and road conditions but on average has any one worked out eg driving at 60mph you get 33mpg, driving at 70 you get 29mpg, driving at 80mph you get 25mpg
so in this case the most optima speed would be 60mph

I am minded to remember a Top Gear programme where at 80mph a BMW 330D was more energy efficient than a Toyota Prius over eg 100km

with the SL also having a large engine would the same be true that higher speed= better energy consumption UPTO a certain point.

Has Anybody found the Sweet Spot they would care to share please?

Thanks and happy motoring

 

[Flyinspanner]

So many variables.
just ensure your tyres are correct pressure, don’t accelerate hard, anticipate, so you don’t have to brake too hard.

Only drive downhill.

 

[Fastcar155]

Hi , as stated earlier so many variables but I even keep all of my petrol receipts from new.

City driving 20 mpg

Long distance in UK 35 mpg

Long distance in Spain 45 mpg.

The are all from the computer but occasionally I check brim to brim and similar figures obtained.

I always use 99 octane

Why the Spanish figures are better I have no idea.

Car C207E400

 

[Larkone]

Which way is the wind blowing for this test? Uphill/downhill/flat? Ambient temperature? Straight road or curves?

 

[jpwilliams]

HI, Given we are all facing high fuel costs I wondered if anybody had done a break down what is the Optimum Speed for Optimum MPG? driving an SL350 R230 model?

Obviously it is affected by driving style and road conditions but on average has any one worked out eg driving at 60mph you get 33mpg, driving at 70 you get 29mpg, driving at 80mph you get 25mpg
so in this case the most optima speed would be 60mph

I am minded to remember a Top Gear programme where at 80mph a BMW 330D was more energy efficient than a Toyota Prius over eg 100km

with the SL also having a large engine would the same be true that higher speed= better energy consumption UPTO a certain point.

Has Anybody found the Sweet Spot they would care to share please?

Thanks and happy motoring

It is 56mph Z although you may not appreciate it !

 

[m80]

It is 56mph Z although you may not appreciate it !

I'll bet it's not for the 639,
somewhere between 45 / 45mph would be best returns, on the flat, little or no wind.

 

[Mactech]

There are just so many variables to quote a most economical speed for any car. How often do you travel in the optimum conditions of no wind, level road, no traffic, warm day etc?
One thing that has not been mentioned is that economy is almost always better when the car is in the highest possible gear, which means in most auto cars this will be above 60mph.
Best to live in the real world and use a certain amount of 'conservation of momentum' and anticipation.

My Easter motoring started with the 'benefit' of a 2 tonne limo with vast frontal area and almost 300bhp.
To mitigate this, the Audi A8 is a mild hybrid, with a good coef. of drag.
I cruise normally at the legal limits as it appears safer, quicker and frustrates other road users much less.
My tyres are lower pressure than recommended as it improves the ride and I never use anything but the cheapest diesel...
These figures include two trips from Norfolk to Wales, 6 x cold starts and some local running around over the Easter weekend.
The official figures for the car are just a smidge under 40mpg. My fuel computer is verified frequently and is always within 1%



My golden rule for driving in normal conditions is that if I have to brake, I have failed to anticipate the road or traffic conditions correctly.

 

[E55BOF]

I would think the most economical speed for any car is not much affected by the various variables, though the actual economy achieved is. Aircraft manufacturers' data includes best range and endurance speeds for their aircraft, but depending on the wind direction and speed, the actual distance covered varies, but the indicated airspeed remains the same. I would think the same would more-or-less apply to cars.

 

[Ted]

I understood it to be the lowest speed in the highest gear without the engine labouring.

 

[ALFAitalia]

Flat out of course..........that way you will get there sooner so your engine wont be running for as long!!! Boom!

 

[zentrex]

Which way is the wind blowing for this test? Uphill/downhill/flat? Ambient temperature? Straight road or curves?

Just a normal 300miles trip from south to north on motorways- I m not trying to find the best possible road test just an average long journey with an old 3.7L engine

 

[m80]

Download the Torque app to an Android.
By an EML327 BT plug in sender.

You would need to create a profile of your car in the app.
You can then monitor such as 'spot' consumption, 'average', speed, revs, and I monitor altitude, as descending or climbing clearly would make a difference.

With comparison to your OBD average consumption, over a distance, you can enter a correction factor. That would make it more accurate.

Even w/o the correction, and although it may not be bob on anyway, the 'spot' comparisons at various speeds would show the change in fuel efficiency.

 

[zentrex]

Download the Torque app to an Android.
By an EML327 BT plug in sender.

You would need to create a profile of your car in the app.
You can then monitor such as 'spot' consumption, 'average', speed, revs, and I monitor altitude, as descending or climbing clearly would make a difference.

With comparison to your OBD average consumption, over a distance, you can enter a correction factor. That would make it more accurate.

Even w/o the correction, and although it may not be bob on anyway, the 'spot' comparisons at various speeds would show the change in fuel efficiency.

ok thanks for that ill give it a whirl