Optimal speed for economical m'way driving?

Pew_Pew_Pew_Lasers!

If they lower the limit to 60mph I shall increase my average speed by 10mph.

michaels

scbk wrote: »

I've driven about 60,000 miles in the last 18mths with a target speed of 60 (about 57 in real life), and funnily enough I didn't take days to get everywhere/fall asleep/die of boredom etc.
Purely for money reasons, I'm not too bothered about speed limits, my nsl is 50 but I'll do 60 unless it's not safe to do so

60 k miles at 60 has taken you 1000 hours, had you gone at 80 you would have saved 250 hours to spend with your family - may be you don't like to spend time with them? For me the extra time with my family is worth much more than the extra cost of petrol.

scbk

michaels wrote: »

60 k miles at 60 has taken you 1000 hours, had you gone at 80 you would have saved 250 hours to spend with your family - may be you don't like to spend time with them? For me the extra time with my family is worth much more than the extra cost of petrol.

Yes but it would've cost me a small fortune extra in diesel. If I wanted to spend time with family/friends I'd be on the dole;)

AdrianHi

greenman7 wrote: »

I came across this on whatcar.com I think it is quite relevant for optimal speeds for m'way driving.
Fuel economy: making every gallon count - Motorway driving

06 June 2008



It's a bit of a pain that economy nosedives as we go faster, since motorways are intended to get us to our destinations quickly.

A steady cruise is also the most efficient way to drive. However, pootling along at 30mph would be a drag and probably not very safe.

You might find yourself in trouble with the law, too. In January, a 58-year-old woman was banned from driving for a week after being caught driving at just 10mph along the M32.

Still, the motorway is where the biggest savings are to be made. Realistically, in good weather and traffic conditions, drivers do over 60mph. It's how much faster you go that matters to your pocket.

Take a small family car like the Nissan Qashqai. At 60mph you'll be doing 39mpg, yet at 90mph you'll be doing about half that.

Yes, you'll get where you're going a bit quicker, but you'll be throwing away an extra 11p every mile. That's £10 on a 90-mile journey. Do that a couple of times a week and it could set you back an extra £1000 a year.

It's not only money you'd save. The UK Energy Research Centre estimates that proper enforcement of the 70mph limit would slash CO2 emissions by 3.7 million tonnes.

Lowering the limit to 60mph would cut CO2 by a further 3.5 million tonnes. That's the equivalent of taking three million Ford Focuses off the road.

Lets hope that total CO2 saving is not based on what the Quashqai will do. A Petrol Mercedes C180 Automatic does more mpg at 120mph than most diesels do and it's mpg at that speed is nothing like half what it does at 60mph, it's more like 2/3.
You can design a car such that the mpg dos not drop off so quickly as you go faster. My car at a constant indicated 75mph (about 71/72mph true speed) returns about 50mpg. At an indicated 85mph it's 48/49mpg, not a lot different. My brother's less powerful and similar size and weight car would do 50mpg at 75mph but it plumets to 38mpg at 85mph.

The_Undercover_ADI

Pew_Pew_Pew_Lasers! wrote: »

Also completion of an IAM course and passing their test,....

I'd just like to point out that the Institute of Advanced Motorists do not advocate breaking speed limits for any drivers apart from emergency response drivers either responding to a call or during essential training. All of the advanced driving organisations now recognise the need for eco-driving and are adjusting all of their syllabus's to reduce the importance of "making progress".

In response to the OP I would suggest travelling just slightly quicker than the trucks, planning further ahead than normal and looking for good gaps where steady progress can be made while overtaking.

Going for the brakes as you get too close to vehicles in front is the equivalent of throwing fuel away - plan earlier and ease off the gas earlier.

Some well trained drivers will be safer at 90 than other drivers at 50, but the fact is that for one individual, driving at a lower speed WILL be safer. Simply reducing your speed from 70 to 60 (a 15% reduction in speed) will reduce your braking distance by 25%. Inherently safer.

sarah_elton

tomstickland wrote: »

Most shunts are the result of cars being too close together. You'll regularly see in it in the middle lane where cars are almost touching.

This winds me up so much! I always leave a big gap between me and the car in front, and the higher the speed the bigger that gap.

I HATE people who get up my backside. I keep an eye out behind and pull in when safe if some idiot doing 120 wants to get past me. People doing the same speed as me do not need to be six inches off my back bumper. :mad:

Pew_Pew_Pew_Lasers!

The_Undercover_ADI wrote: »

I'd just like to point out that the Institute of Advanced Motorists do not advocate breaking speed limits for any drivers apart from emergency response drivers either responding to a call or during essential training. All of the advanced driving organisations now recognise the need for eco-driving and are adjusting all of their syllabus's to reduce the importance of "making progress".

Of course, however they are primarily an organisation for improving driving standards, in actual fact the focus on obeying speed limits both on the course and in the examination is practically non-existent. My test with a police advanced driver had me regularly breaking the speed limit, he did mention it however he also mentioned I had done it entirely safely and appropriately, and therefore didn't mind one bit.

The_Undercover_ADI wrote: »

Some well trained drivers will be safer at 90 than other drivers at 50, but the fact is that for one individual, driving at a lower speed WILL be safer. Simply reducing your speed from 70 to 60 (a 15% reduction in speed) will reduce your braking distance by 25%. Inherently safer.

And improving driving standards with extra training and increased police patrols will result in safety improvements far beyond a simple 10mph reduction in average speed. Speed limits are lowest common denominator safety enforcement - and achieve little, if nothing.

Pew_Pew_Pew_Lasers!

sarah_elton wrote: »

This winds me up so much! I always leave a big gap between me and the car in front, and the higher the speed the bigger that gap.

I HATE people who get up my backside. I keep an eye out behind and pull in when safe if some idiot doing 120 wants to get past me. People doing the same speed as me do not need to be six inches off my back bumper. :mad:

Why are you not pulling in regardless? What are you doing in an overtaking lane in the first place?

Smi1er

I've read this with interest.

I used to be one one the speeders. On a motorway I would drive at 99mph, knowing if I got caught I wouldn't get banned. If there was no traffic I would exceed 100 on a regular basis. Driving at 70 bored me, I always said I wouldn't look where I was going due to boredom. Speeding saved me time.

Then seven years ago I finally stopped. No reason really. I then drove at 75... and guess what! I got there almost as quick, but more importantly I arrived less stressed and less tired. Driving at 99 is stressful. I consider myself an above average driver and the faster you drive, the more distance you are covering in relation to time, the more you have to concentrate and that in itself is tiring.

Now I just set the cruise and it amazing how many cars overtake you only to slow down up the road etc.

Someone said that driving a 180 mile journey at 90 instead of 70 saves them 45 minutes... WRONG. Do the maths it doesn't fit, nor is the journey at a constant speed. Yes you might well get there quickly than me, but I will arrive fresher.

Don't get me wrong I'm not someone who thinks that speed kills, it doesn't. It's inappropiate use of speed that kills

If someone behine me comes up at 90 I don't care. I'll pull in to let you pass as soon as it's safe to do so and let you pass.

Onto the OP... different cars, different gearing, so there is no real answer, but if you do anything less than 60 on a motorway then it's rather dangerous (unless you're towing something)

cyclonebri1

Pew_Pew_Pew_Lasers! wrote: »

Of course, however they are primarily an organisation for improving driving standards, in actual fact the focus on obeying speed limits both on the course and in the examination is practically non-existent. My test with a police advanced driver had me regularly breaking the speed limit, he did mention it however he also mentioned I had done it entirely safely and appropriately, and therefore didn't mind one bit.



And improving driving standards with extra training and increased police patrols will result in safety improvements far beyond a simple 10mph reduction in average speed. Speed limits are lowest common denominator safety enforcement - and achieve little, if nothing.

You're never wrong are you?