40mph motorway speed limit?

Currently reading:
40mph motorway speed limit?

Hellcat said:
But my car is less efficient and polutes more at 40mph than it does at 70 :confused:
At a sustained 40mph no, however every time I've experienced an enforced 40mph limit, on the A14 around Cambridge, the V70s last 100 mile fuel economy has dropped to the level of a sustained 130km/h cruise! As for safer?.. Drive down the M11 with a 50mph limit everything is so cramped and congested you just can't make space, with cars at a lorry length or less between each other, if someone has to brake hard it's probably gonna hurt.
 
StoneNewt said:
At a sustained 40mph no, however every time I've experienced an enforced 40mph limit, on the A14 around Cambridge, the V70s last 100 mile fuel economy has dropped to the level of a sustained 130km/h cruise! As for safer?.. Drive down the M11 with a 50mph limit everything is so cramped and congested you just can't make space, with cars at a lorry length or less between each other, if someone has to brake hard it's probably gonna hurt.

at 40 its not really gunna hurt....
 
X reg BMW5 series, impact speed 35~40mph, a rear impact... the victim was off work for 3 weeks with whiplash and has never got over the lower back problems. The BMW was a write off what did this?.. A 53 plate Corsa.
 
StoneNewt said:
X reg BMW5 series, impact speed 35~40mph, a rear impact... the victim was off work for 3 weeks with whiplash and has never got over the lower back problems. The BMW was a write off what did this?.. A 53 plate Corsa.

thats just silly, i was rear ended in the uno, my mate hit me doing 40mph while i was stopped at lights, neither me or my passenger sustained any real injurys that laster more than a few days (just felt a little sore)
 
you mean he was doing a sustained 40mph without braking into the back of you?.. a real 40mph impact carries a fair old weight.
 
Do this little test... get up to about 70 on a nice piece of private land and stand on the brakes to lock up and watch the speedo!... it'll probably be about 1/3~2/3 of a second behind what's actually happening... you'll also notice that with the wheels locked the speedo will read 0... I've done it enough times.

Also the only way to judge the actual impact speed is to look at damage etc. 35~40mph was the assessed impact speed from the police.
 
Last edited:
StoneNewt said:
Do this little test... get up to about 70 on a nice piece of private land and stand on the brakes to lock up and watch the speedo!... it'll probably be about 1/3~2/3 of a second behind what's actually happening... you'll also notice that with the wheels locked the speedo will read 0... I've done it enough time

yeah i know, same as you do a burn out and get to 60 ;)

by the by - dont try to get it in third doing a burnout
 
they wouldn't lower it. the government would lose too much money. sposedly at 40 less fuel would be used, the government doesn't just have the tax on petrol to try to limit consumption. also currently the motorways are the safest roads in britain i believe. also businesses would be hugely affected. it's just someone throwing up an idea to try and gain themselves publicity.

on the subject of inaccurate speedos. going over the severn bridge when wet. the metal strips can cause wheelspin. :p
 
Last edited:
nope, most cars are at their most economical at around 55-65mph, where the car is not revving that hard, and air resistance is only just starting to affect anything.
if your car can do 110mph and its more economical than it is at say 60mph, I'm noddy holder:D


and bulldog, your car is lame if it can't burn out in 3rd:D
t'old 2.0 NA volvo can do a burnout, in 3rd, reading 65mph+ whilst towing an 1800kilo merc estate:D :D :D *












*whilst in a deep mud pond in kazahkstan, it was either this really steep sided gulley, or a 4car length mud pit, went for the mud pit at abou 40mph, couldt' see sht (mud everywhere instantly), cars pretty much instantly got stuck, yet rear wheels (RWD) stayed alight, after abou 20sec's at WOT it managed to get to about 65mph at the wheels and was actually moving forward, just. had to start the merc with no oil in it (just muddy water, since sump had a hole the size of your fist in it!) to pull each over out the pond.

great fun!!! really shat the merc up too!!! volvo just got a bit here and there, but near 70mph of roostertail for a good 3-4minutes made a right shtty mess of the merc:slayer:
 
faster4_tec said:
nope, most cars are at their most economical at around 55-65mph, where the car is not revving that hard, and air resistance is only just starting to affect anything.
I'd think that most cars would be the most economical at the lowest rpm they can hold in top gear, however the 'sweet spot' is around 55-65mph, go below that and the economy doesn't improve much, go above that and it'll start getting thirsty.
 
Back
Top