Fuel Economy

[Charles]

I was getting angry this morning reading about some pretentious Transport for London spokesman talking about fitting speed limiters to company cars and stating that this will improve fuel economy and save the planet ...

This got me thinking about the results from the Rolling Road Day last Saturday, because we were provided with fuelling curves as part of the results.

Looking at mine, it appears that the leanest fuelling occurs at about 4000rpm - which, if I have interpreted it correctly, suggests that my car is most fuel efficient at that point.

If that is the case, is it then a reasonable extrapolation to say that optimum fuel economy is reached at about 110-120mph

We have had many members posting about fuel economy and virtually all of them suggest that they get best MPG between approximately 80 - 120 mph - where permitted, of course.

Is this perhaps the reason - that our cars are optimised for running at say 100mph? Average speeds on Autobahns are higher than in the UK and so, again, it feels reasonable to assume this...

I don't know, but I am getting sick and tired of the holier than thou people who make sweeping statements about lower speeds will save the planet etc

Rant over - for now

[neil]

Yeah there is a huge amount of spin with the environmental issues. I know walking around the IAA (frankfurt motorshow) virtually ever manufacturer was showing off their hybrid models bluetec / bluemotion / CDI / CGI / Hydrogen - you name it. The main aspect was the co2 argument and that as we know is not the whole story but the one that has caught the publics imagination.

It's interesting as even I feel effected by it all. I know that the UK has a miniscule effect on the world's situation and that being in the UK makes my 'carbon footprint' even more inconsequential (We have to take the moral high ground though!), I also know I like cars (just a little!) but even we these two facts firmly in my head and the fact that I am far than convinced that Humans are to blame for the changing climate. I still feel completely unable to buy a 4x4 – it’s an alternative to a MPV but you almost feel like you’ll be stoned or put to the gallows for even uttering such heresy!

The fact is that cars are built with different criteria – a Bugati Veyron is not built for fuel economy and a smart car isn’t built for motorways. However we do know that ALPINAs are built to perform and be economic, so that should make us all feel better.

You always have to laugh at the 2CV driving hippies as it is a truly awful engine and pollutes far more than a large modern car.

As for the theory that an ALPINA is more fuel economic at higher speed it wouldn’t surprise me – perhaps the next time someone gets caught speeding they can claim it’s all in the name of the environment.

PC: Do you realize what speed you were doing sir?
Sir: Yes 120mph – I get the best fuel economy that way
PC: Right you are sir, be on your way

Well you can dream can’t you !

[Charles]

PC: Do you realize what speed you were doing sir?
Sir: Yes 120mph – I get the best fuel economy that way
PC: Right you are sir, be on your way

Like it

[blacky]

there are to many people in high places with to much time to thing of stupid ways to piss the population off
i work for toyota so most of the customers are older people (as there is not sporty models at the mo) that tootle around at 40 mph as to them this is still way to fast

the sales men give all the speel about how good for the enviroment the hybrid cars are but in reality they are a piss poor 15 petrol engine that charges a battery cell that is most of the rear of the car & also adding a hell of a lot of weight to the car & every one i have seen has poor MPG so when you think about it they are really bad for the enviromet as they are crap on fuel & when they reach the end of there lives they have a lot of nasty things that need disposing of

[sclarke]

It also annoys me, all this focus on co2. co2 is only one issue. Fossil fuels used to be the issue (when they would run out etc).

The people that annoy me the most are the drivers who do 40k a year and then claim to be helping the environment by buying a car that does 10% better on its co2 test. Why not just drive 30k a year and manage your trips better, that would be better for a lot more reasons than just co2. Less congestion, less fuel used, less wear on the roads.

The second lot are those that buy a diesel and pretend it is for environmental issues and then chip it. As I understand it the way chipping can improve your power is to avoid the nasty environmental restrictions built into the ECU to give it that low co2 emission.

The truth is the government are loving it. Co2 is a cash cow.

However, if you set your cruise control in fifth at 2000 rpm I guarantee you will get better MPG than at 80-120 mph.

Bloody aerodynamics.

[simon13]

average autobahn speeds is 110mph and it's readlily apparant driving new german cars that they are built to cruise at 3 figure speeds and return respectable economy, hell even my E30 325i will do low 20's at 100-120mph. But the revs are higher. Not an issue with the newer cars and their mega overdrive 6th gears these days.

I think your a fool if you believe diesels are better for the enviroment, when i follow a 55 plate new diesel car giving it some and their is plooms of smoke coming out the back, i don't need to know anymore. As they all do this from new

[nealpina]

This could be considered to be off topic but I believe it is a valid point. After driving in Europe I don’t want the government to increase the national speed limit because everyone undertakes, does not move from the outside lane, and on the M25 I always get some Chav trying to prove how fast their 1.1 hot hatch is. IMO I personally believe (not us but as a nation) we don’t have the driving skill or discipline to drive at those speeds in this country. However if we were allowed to drive at those speeds would the average driver drive with due care? What makes me mad is that I believe we have more speed cameras than the rest of the world.

Seriously for safety and mainly for our own human rights this technology should not be in our cars (personal or company cars). Especially if they have GPS than no matter what road 30 or national speed limit - the car will not go above this speed therefore we will be robots!!!

[Charles]

Neil,

It's not really "off topic" at all.

We have a good road infrastructure which would be able to take many more vehicles at higher average speeds IF people were able to drive better and were more aware of others around them.

Last Saturday, I travelled down to the Rolling Road Day and spent most of the journey thinking about how pleasant Lane 1 looked whilst I was sitting in Lane 3 waiting for the traffic to pass the cars in Lane 2 who clearly had an aversion to moving into Lane 1.

Then when there was an opportunity for the car in Lane 3 to move across (it only needed to be very briefly) into Lane 2 to let me pass, they then try and wring an extra 2 mph out of their car in order to stay in Lane 3.

The driving test needs to be improved, driver reassessment needs to be implemented every 10 years and Lane 2/3 hogging needs to be dealt with by more marked police patrols - its amazing how lane discipline magically improves when a jam sandwich is travelling in Lane 1.

Remember also that most autobahns are two lanes and the average speed is much higher.

As drivers, we (collectively) are our own worst enemies and continue to feed the spurious arguments offered by politicians in order to levy more and more indirect taxes on us.

[sclarke]

The driving test needs to be improved, driver reassessment needs to be implemented every 10 years and Lane 2/3 hogging needs to be dealt with by more marked police patrols - its amazing how lane discipline magically improves when a jam sandwich is travelling in Lane 1

IIRC when I took my driving test the speed limit was meant to be adhered to. That hasn't however stopped me breaking it on occassion. In the same way most people do know what they are supposed to do on a motorway but they break the rules. Re-testing people will not make them better drivers it will just make them better at passing the test. The fact that people do the right thing when a police car appears surely proves this?

[Charles]

IIRC when I took my driving test the speed limit was meant to be adhered to. That hasn't however stopped me breaking it on occassion. In the same way most people do know what they are supposed to do on a motorway but they break the rules. Re-testing people will not make them better drivers it will just make them better at passing the test. The fact that people do the right thing when a police car appears surely proves this?

Fair points - but what if being able to retain your licence/getting insurance depended on it?

At the moment, many drivers see being able to drive as a right rather than a privilege. As such, once on the road they do what the hell they like without taking into account those around them. How many people think about the braking distance required for the juggernaut they have just pulled in front of at the approach to a roundabout - for example?

I believe that if drivers respected their own ability to drive more than they currently do, then things would improve quite dramatically and quickly.

[sclarke]

I guess my point is how can I criticise someone for breaking the rules when I also break the rules. Which rules I break and my perception of their seriousness is largely irrelevant.

going back to your original topic though...

I have tried driving at the speed limit on the motorway and it is an interesting experience. The fuel economy was considerably better (33mpg as opposed to the regular 24mpg). It was quite relaxing on most journeys and I hardly ever got stuck behind people in the outside lane.

I actually think it would do company car drivers the world of good to be restricted to the speed limit and has a lot of potential benefits. I couldn't really care less whether it is supposed to be better for the environment, but I do think it could have a lot of other advantages like less stress, less expectation on employees to break the speed limits, better fuel economy. I am surprised it has not been brought in for legal responsibility reasons already, after all the company directors could be held responsible for the consequences of a speeding employee?

I know this is not a popular view but don't dismiss it just because of the environmental label.

[Chas]

I am surprised it has not been brought in for legal responsibility reasons already, after all the company directors could be held responsible for the consequences of a speeding employee?

I know this is not a popular view but don't dismiss it just because of the environmental label.

I understood this has already happened - in cases of van, truck and even bus drivers whose schedules have been shown to be impossible to attain without speeding. Having a company imposed schedule which is unrealistic at legal speed has given rise to comanies being held responsible and fined. I'm not sure if it has gone as far as holding individual directors responsible but that can't be far away if they have a duty of care to their employees etc.

Company car drivers are another matter and generally set their own schedule rather than work to a timetable.

My biggest issue with 'speeding' is the grey area between 70 and 90mph. I've seen people stopped (or flashed) at 75mph and I've also witnessed a patrol car ambling down the inside lane of the M6 at 80mpn whilst the general flow of traffic passed him at higher speed.

I'd like to see a realistic limit imposed (say 85mph) and consistently enforced.

[blacky]

i think a simple law like if there is someone behind you in the middle or outer lane you have to move out over if safe to do so would help a lot

as most jams are caused by people sat in the middle or outer lane when the inner is empty

i no its off topic a bit but stopping & starting is also not good for economy

[Alpina Jim]

Quote "I actually think it would do company car drivers the world of good to be restricted to the speed limit and has a lot of potential benefits."

My employer is now having all new vans supplied speed limited to 70mph and signage fitted to the rear of the vehicle to let other road users know, apparently it is for the good of the environment or so I have been told.
This should prove to be interesting as all our vans are white and perhaps this is the beginning of the end for white van man as we know him.

[blacky]

as with most elecrical toys if people fit them other people will find a way round them