Optimal speed for economical m'way driving?

therivierakid

Does anyone know what it is, assuming you want to actually get somewhere in a reasonable time without having artics bearing down on you all the time?

tinkerbell84

Depends on the car.

I rarely do below 90 on the motorway, anything less is a waste of petrol!

404

therivierakid wrote: »

Does anyone know what it is, assuming you want to actually get somewhere in a reasonable time without having artics bearing down on you all the time?

I did drive at 55mph once and slipped streamed a few trucks... I managed 32mpg in a 4 litre Jeep cherokee... not too bad really though it was more of an experiment.

Driving at 60 I get 26.

kitchpoo

Cars consumtion figures used to be set differently, and a figure used to be produced for travelling at 56mph, and as a consequence gearing used to be set for this to be the optimum. But now with this figure lost in time there is no need for manufacturer's to gear like this, but I have found 56 to be comfortable and economic still without feeling far too slow for the flow of traffic.

Charlton_Taz

Been experimenting with this on my commute (which is mostly motorway driving) for the last couple of weeks. Travelling at 60mph means I can get 65-70 miles per gallon out of my skoda....which I think is pretty fab!

shown73

I've never had the nerve, or patience, to sit at 60/65, but I do know that there is quite an increase in consumption from 70/75 to 80/85. I've proved it on a number of long journeys, but it does take a bit of willpower to sit at 70 on a long straight motorway. On a luton type van, the difference was collosal between flat out and a bit less. Nearly ran out of fuel once or twice. On a long journey, a light foot does have quite a benefit, and of course this is becoming ever more relevant for those of us who actually pay for our fuel out of net income. Old 2litre Mondeo is perfectly happy to sit at 85 all day, but there is a price to pay.

tomstickland

I used to drive at 80ish and more whenever on the motorway, but I've recently been using 70 indicated, which shows as +50mpg. If the conditions allow and I'm really zoned in on the economy I'll dip down to 65. I don't think I'd bother going much lower.
The work required to move the car is a function mainly of aerodynmaic drag, and that increases with speed cubed. So fuel consumption is roughly proportional to speed squared (because you spend less time consuming fuel at the cubed higher rate when you go faster).

michaels

Does nobody value their time more than a few quid saved on petrol?

tinkerbell84

michaels wrote: »

Does nobody value their time more than a few quid saved on petrol?

I do!!!

That's why the 90mph average for me!!

As long as this lot don't hog the middle lane I'm happy!

Conor_3

It's not even a few quid on petrol you're saving and depending on your driving style, any savings from going slower could be cancelled out by the way you drive.

mum2one

When we go South West on hol, 200 mile drive, me I go 65/70, father does 55-60, 70 is there for an absolute emergency only situation, (same car 1.6i), 1994 car, I hate to admit this but there is a markable difference in petrol, about 1/8th to 1/4 tank difference in his favour!