Speed limit on motorways.
- Thread starter gavroche
- Start date
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tommaguzzi
Über Member
- Location
- County Durham
Wow bloody hell every day is a school day!
I honestly never realised you caravaners drafted lorries!
I will look out for that now. Thanks for that.
OP
OP
gavroche
Getting old but not past it
- Location
- North Wales
60 mph = 70mpg
Drago
Legendary Member
- Location
- Suburban Poshshire
Most cars will give excellent economy at an indicated 60, which is more like a real life 56, because the extra urban test is conducted at that speed so they tweak the engine map to suit the test.
OP
OP
gavroche
Getting old but not past it
- Location
- North Wales
[QUOTE 4811189, member: 9609"]how have you calculated that and what figures did you get for 40 & 50 mph ?[/QUOTE]
40would be in 4th gear so higher fuel consumption.
Don't know at 50, too slow on dual carriage / motorway.
40would be in 4th gear so higher fuel consumption.
Don't know at 50, too slow on dual carriage / motorway.
marzjennings
Legendary Member
- Location
- Houston, Texas, USA
Which means when I fly home to see family and have to drive from London to Cornwall to see family I'm driving on my US license rather my old UK license. I wonder how points get applied to a US license?
PaulSB
Squire
- Location
- Chorley, Lancashire
I can only offer practical rather than technical experience. I use cruise control whenever practical. When using CC I can see the fuel consumption on the flat is steady and reduces on descents. Yes consumption increases on inclines s but this would be true without CC and I feel is compensated for on the flat/descents.
If I drive at the same speed without CC I can observe fuel consumption varying constantly. I put this variation down to the difficulty for a driver of keeping exactly the correct pressure on the accelerator pedal to maintain a constant speed.
My view is a machine is better placed to maintain a constant speed than a human who faces two difficulties in achieving this - applying a constant pressure and not being distracted by all that is happening around him/her.
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I don't tuck in too close, it's not necessary. If I monitor my on board fuel consumption readout I can find the optimum distance to follow. The sweet spot is further back than you would think.
Best ones to follow are the tall curtain siders that are limited to 100 kph/56 mph. Their draft goes back a fair distance - certainly one that's safe to follow and still make a significant improvement in fuel consumption. This is ideal as the towing speed limit on a motorway is 60 mph.
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Does your drafting conflict with the "two second rule" advice?
I just knew someone would come up with that.
Drafting usually works out at about one and a half seconds.
Tell me, how many vehicles do you honestly see following the two second rule on a motorway - or anywhere else for that matter?
Apart from you, of course.
Drago
Legendary Member
- Location
- Suburban Poshshire
I try to do so Papa Dirkie, because of my police ninja driver training, but its blummen difficult because if you leave a sensible gap some plum sticks their car in it.
Exactly.
I do the same as you and for very similar reasons.
Following a professional driver, travelling at a constant speed in a large lorry, in lane 1, at 1 1/2 seconds is probably a lot safer than following Plum Boy in his BMW at 2 seconds at 80 mph in lane 3.
Drago
Legendary Member
- Location
- Suburban Poshshire
I tend to stick at the NS, find a nice lorry and plug in behind it. Unless the roads are empty, it makes zero difference to journey times on the 120 mile jaunt down to my Dads in Kent, but makes a big difference to fuel consumption and stress levels.
