Thanks dereckr, see your point, but as running costs are subjective, i own the car, bought far below market value, no finance, resale value nil as far as i'm concerned, just the costs of tax, currently £185, insurance £245, annual service was £217 last week, will allow for £150 for 2 new tyres in a few months time, by my calculations running costs were £48.60 + fuel £63, still good for 1 person compared to £67 +£22 for underground tickets. It wasn't really about costs though, it was about the empty roads too!

happy motoring

"train fare would have been £67 each..."

Not wishing to push this thread off topic, but you have omitted the running costs of the vehicle per mile. Of course the car is the lowest cost option for four people, but 46 litres of diesel costs around £63. You should double that figure (at least) for your true cost per mile.

This is the circular argument that always rages about public transport vs running a car. However the fact is that unless you live in a major city which you hardly ever leave, you need a car. When you have got a car you have paid for the running costs ie Insurance, TAX and services so you might as well use it.

I go to see my parents in West Wales regularly, and to do this by rail would cost an arm and a leg, and be grossly inconvenient and time consuming. In the car it is exactly 200 miles, I can do this in 3 1/2 hours. By train I would have to get a TAXI to the station, change trains in Swansea and walk the last 1/2 mile from the final station with luggage etc. Not to mention the limited timetable when you move very far away from a major town.

I'm sorry but I am remaining as 'Mondeo Man' as one of our politicians once put it.

You make an interesting point concerning speed versus fuel consumption but as you point out, your comments are specific to one car model. As I have almost the same vehicle (Skoda Superb AWX) but for a longer wheel base and a slightly heavier body - which is of little consequence under steady state conditions - I thought I'd try to repeat your observations.

To cut to the point, I can't quite achieve a lower fuel consumption under steady state conditions (using cruise) at 80 as opposed to 70 mph. BUT the difference is very marginal - the more so in view of the car's in built measuring equipment. I was surprised by this and thought a little about it.

Although VAG and others will never release proper SFC (specific fuel consumption) curves for their engines, I've tested enough diesels to know that the lowest SFC will nearly always coincide roughly with the engine speed corresponding to max torque. Another factor is the low drag of the B5.5 body. Theoretically the Superb clone should have a lower drag than the Passat because it's longer - but VAG gave up shouting about drag coefficients by the time this car got to the bottom of the model pile and won a Skoda sticker.

So, I suspect your slightly surprising result is a combination of running the engine nearer to its speed corresponding to its lowest SFC and also to the vehicle having a very efficient shape. Many models have either not progressed or have regressed in this respect (SUVs for instance).

Interesting observations - usual conclusions: You can't buck the laws of Physics and careful design pays dividends. The PD was the first car-sized diesel to out perform a fossil fuelled power station in terms of SFC. This highly significant point has been totally lost by the politicians leading to some highly questionable policies.

659.

i spent 18 months cruising on the motorway at 56mph in my lexus LS400 to save fuel...and getting about 18mpg

i was in a hurry one week (just wasn't getting ready in time) so was rushing along at 80mph.....and got 24mpg......

I though ok thats strange so spent next week doing 70mph and got 21mpg then another week doing 80mph and again got 24mpg......i was then annoyed at all the fuel i wasted and time i wasted trying to be more economical, i ow cruise along at 80mph everyday, i'd like to try 90 or 100 when i go to germany one day see how it goes then.

1995 Lexus LS400 4 litre V8 4 speed autobox weighs about 1675kg aerodrag is 0.29 Cd (this is actually fractionally better then my wifes Seat Ibiza Ecomotive that has an aerodynamic kit on it, which gets 75mpg if you have a very good run with no traffic, and then again it's supposed to do 90mpg extraurban....80mpg combined, it gets nowhere near it, My LS is supposed to get 25mpg it gets 20mpg....) 4th gear is designed to do up to about 160mph so i guess the higher speed puts engine into a better torque map.

Why not have the autobahn system they have in Germany.130KM Top speed is advisory.What are the Spanish authority trying to prove save on fuel?And more accidents are caused by drivers driving bumper to bumper.Strange way of making laws a bit like the states where the majority of drivers go faster than 55mph.

Most police if asked outright will admit that they would never nick anyone for doing 80 in good weather on a clear motorway, though I cant vouch for those slimey toad like creatures that sit in their white vans on the bridges !!

I don't know how many people on here have children, but I think it's when they're coming up to 17 and learning to drive or riding about in other youngsters' cars that one becomes acutely aware of road safety issues.

Kid's will drive like tits they always will not much you can do only if you limit learngin till theres a proper attitude test or there 30 will new drivers be "safe" and even then no experience doesn't help.

I can't agree with the point about average speeds cams being a good thing on M-ways, or any other fast road. Generally people use their judgement when it comes to speeds, with the odd glance at the dial to confirm and adjustments where needed. When you make these damned cameras part of the equation suddenly everyone focuses the majority of their attention on their speedo, and only what little remains on the road ahead. To enforce speed limits to the point where people's driving becomes paranoid and artificial is a dangerous thing. People should be allowed to use the judgement that any good driver should have to regulate their speed, within sensible boundaries. If your judgement, innocently or otherwise, allows you stray beyond acceptability, then a punishment is fair enough. Most drivers would manage this without a problem.

I've been pulled for speeding on a M-way, very late in the evening on a clear night, in light traffic. The officers had a word, and then allowed me on my way. They had a perfectly legitimate opportunity to issue a ticket, but they didn't. No ticket, no points. The reason being that my driving, whilst faster than it should've been, was safe in every other sense, in terms of overtaking, distances and general road manners etc. The moral would appear to be that if your driving style is reasonable, then your speed alone, provided it's not stupidly quick, probably won't get you in too much grief. On that basis, the current limit of 70, with an unofficial 'nod' to touching somewhere around 80, seems to work pretty fine most of the time.

I for one am an advocate of raising the speed limit on motorways. The current 70 limit was put in place decades ago. Car technology, brake system improvements (ABS, Discs all round etc) and tyre developments mean that in theory at least you would stop faster and safer from 80mph today than you would have from 70 30 years ago. I find that on any motorway the general flow of traffic is around 80 anyway. Would this increase to 90 with a higher limit? Theres one way to find out!

And why not do what some other countries do and have a lower limit for bad weather? With the increase of signage that can be changed would it be so difficult to have different limits depending on conditions?

Those who drive in excess of the current speed limit will continue to do so whatever the limit. Those who stick to the limit will also do so whatever the limit.

And before anyone comes out with the old "speed kills" nonsense i would say that a more reasonable phrase could well be "inappropriate use of speed kills" Personally i would feel much safer doing 80 or 90 on an empty 3 lane motorway than 30 past a school at going home time. yet im only doing a third of the speed so must be 3 times as safe surely? And within the posted speed limit too!

Edited by amj on 20/03/2011 at 13:14