Jump to content


Major contribuition to road safety and reducing aggressive driving.

Recommended Posts

12 hours ago, Resident said:

Explain why my car does mid to late 60s in MPG at 70mph in 6th gear but drops to late 50s between 55-62mph. Self tested using cruise-control to maintain speed, averaged over same stretch of M1 Southbound, J34-J31. Measurment device car's own onboard computer, reset on slip road for each test. 

Surely you`re not suggesting that any vehicle is more efficient as it goes faster. That`s impossible, as has been pointed out the drag goes up for a start, is it by the square of the speed, I`m not sure. I know the amount of kinetic energy * in a moving body goes up by the square of the speed.

 

* As in how much damage it`s going to do to anything it hits.......

Share this post


Link to post
Share on other sites

In the 1960s about 8,000 people were year were killed on the roads. It's now down to about 2,000 , still a tragic number. About 1/4 of that is speed related.

6% of casualties were on motorways, about 60% on rural roads.

I'm a massive believer in hammering speeding in targeted areas, especially built up ones where there is most danger of pedestrian death or injury.

Motorway speeding is important, but attracts a lot of focus, disproportionate to its accident rate.

Share this post


Link to post
Share on other sites
17 minutes ago, Justin Smith said:

Surely you`re not suggesting that any vehicle is more efficient as it goes faster. That`s impossible,

No that's how it works. Don't confuse thermodynamic efficiency with fuel economy - they are different things.

Share this post


Link to post
Share on other sites
12 hours ago, DT Ralge said:

“More fuel efficient” and  “70 mph” is simply wrong for ordinary vehicles with 5/6 gears.  

Once in top gear at around mid-50-65 the engine is at its most efficient when gauged by mpg figures.  Any acceleration above this speed increases wind resistance and there are no more higher-gear efficiency gains to be had and fuel efficiency drops.  Driving at 85 mph is reckoned to use 40% more fuel than 70mph. 

I'd agree you use more, but not that extreme from 70 to 80 mph change. I recently drove a very long distance in Germany, autobahn, and did long stretches at 100mph+ (legal of course) and used about 25% more than 70mph. Although I have a very long legged top gear.

Share this post


Link to post
Share on other sites

Going from 70 to 100 will require about twice the energy to move the air out of the way.

 

Of course - you are not driving at that speed for as long because you get there quicker so that means that you have to allow for that as well... 30% extra fuel is the number I arrive at which is fairly close to your 25%

 

 

Share this post


Link to post
Share on other sites
21 minutes ago, Obelix said:

Going from 70 to 100 will require about twice the energy to move the air out of the way.

 

Of course - you are not driving at that speed for as long because you get there quicker so that means that you have to allow for that as well... 30% extra fuel is the number I arrive at which is fairly close to your 25%

 

 

Yes, it could well have been 30% more. I didn't do a like for like for equivalent stretches, so it's a guestimate, in that ballpark.

Share this post


Link to post
Share on other sites
1 hour ago, woodview said:

In the 1960s about 8,000 people were year were killed on the roads. It's now down to about 2,000 , still a tragic number. About 1/4 of that is speed related.

I would be interested what definition they use for "not speed related". Particularly in view of the fact I`m certain that if no vehicle was able to break the speed limit it would hugely reduce aggression on the roads, and it`s aggressive driving which causes most deaths.

 

The death figures my have dropped significantly since the 60s, but it`s still far too high. I`m pretty certain any family members of anyone killed on the roads would not be comforted in the least that death rates had dropped by a 3/4 or whatever.

Edited by Justin Smith

Share this post


Link to post
Share on other sites
37 minutes ago, Justin Smith said:

I would be interested what definition they use for "not speed related". Particularly in view of the fact I`m certain that if no vehicle was able to break the speed limit it would hugely reduce aggression on the roads, and it`s aggressive driving which causes most deaths.

 

The death figures my have dropped significantly since the 60s, but it`s still far too high. I`m pretty certain any family members of anyone killed on the roads would not be comforted in the least that death rates had dropped by a 3/4 or whatever.

I don't know how they quantity ' speed related' , but I do believe they are reporting it from an impartial perspective.

As I said in the post, 2000 is a tragic figure. I also said, i believe in hammering speeders, particularly in built up areas where pedestrian s are present. At the same time this is a very intrusive method, and I mentioned snoopers charter, cctv, but could also talk about fimgerprint and dna storage. How do you think the topics overlap?

Share this post


Link to post
Share on other sites
3 hours ago, woodview said:

I don't know how they quantity ' speed related' , but I do believe they are reporting it from an impartial perspective.

As I said in the post, 2000 is a tragic figure. I also said, i believe in hammering speeders, particularly in built up areas where pedestrian s are present. At the same time this is a very intrusive method, and I mentioned snoopers charter, cctv, but could also talk about fimgerprint and dna storage. How do you think the topics overlap?

I think stuff about mentioning "snoopers charter" and stuff as a means of arguing against speed limiters is the kind of poor argument usually advanced by Petrolheads because, let`s face it, they don`t have any other argument. As far as I`m concerned a car is a lethal weapon and driving one is a privilege in which everything should be subsumed to minimising risk for other road users (including pedestrians). TBH I`m not that bothered about the driver himself (aggressive drivers usually are men) putting themselves at risk, it`s others they put at risk (who have no choice in the matter) who I have sympathy for.

Share this post


Link to post
Share on other sites
7 hours ago, Justin Smith said:

Surely you`re not suggesting that any vehicle is more efficient as it goes faster. That`s impossible, as has been pointed out the drag goes up for a start, is it by the square of the speed, I`m not sure. I know the amount of kinetic energy * in a moving body goes up by the square of the speed.

 

* As in how much damage it`s going to do to anything it hits.......

No. I was dispelling the common myth that ALL vehicles are most fuel efficient at 56mph. 

Share this post


Link to post
Share on other sites
2 hours ago, Justin Smith said:

I think stuff about mentioning "snoopers charter" and stuff as a means of arguing against speed limiters is the kind of poor argument usually advanced by Petrolheads because, let`s face it, they don`t have any other argument. As far as I`m concerned a car is a lethal weapon and driving one is a privilege in which everything should be subsumed to minimising risk for other road users (including pedestrians). TBH I`m not that bothered about the driver himself (aggressive drivers usually are men) putting themselves at risk, it`s others they put at risk (who have no choice in the matter) who I have sympathy for.

I agree in making roads as safe as possible and cracking down on dangerous driving.

But a gps enabled vehicle vould also automatically issue you speeding fines, quite simply. So the safety principle is great, I agree totally, but I struggle to differentiate that and snooping, dna storage etc etc that have all been hotly disputed.

Share this post


Link to post
Share on other sites

I'm totally against this. The technology just isn't ready and it's highly intrusive. Furthermore it takes away any discretion (e.g. a clear motorway in good conditions) which of cause all posters here would not partake in, but a large proportion of motorists in the real world safely do.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.