'It isn't pollution that's harming the environment. It's the impurities in our air and water that are doing it.'
- George W. Bush

There you go then.

<blockquote><cite>Posted By: adwindrum</cite>
Lets all drive smaller cars, less and slower, and tax the hell out of bigger cars - serious tax of £4-500 not just an extra £100 for a £50,000 4x4 truck!</blockquote>
That should read £4,500! Unless you have a job that requires you to drive in mud - e.g. builder, survey. farmer, small holder. Taking 6 kids to school doesn't justify a 4x4 - a Megane Grand Scenic 1.6Dci is enough for that. Cost less and gets nearly 50mpg.

Posted By: TimberFreewheeling is bad!
Whatever you think to the contary, leaving the car in gear while slowing down is more fuel efficient and much safer

Not only is freewheeling bad, it's also illegal in the UK as the highway code clearly states that a driver must be in control of the vehicle at all times. If you coasted at any point in your driving test, you'd quite rightly fail. I was in a car with a friend years ago who thought coasting was the way to go - we were going down a hill and by the time we got to the bottom smoke was pouring out of his brakes. Luckily we were able to come to a stop at the junction at the bottom, but it was a close call. Brakes are for coming to a stop - all other speed control should be using the accelerator (either increasing or decreasing). If you need to use the brakes then you're not paying attention (or, before I get jumped on, an emergency situation arose that required action). I can drive in heavy traffic and almost never need to put the brakes on. Of course, all bets are off if you're stuck in an automatic - but note that an automatic transmission never coasts either - if it was truly better, you'd think the autoboxes would do it. But they don't. Anyone that thinks coasting is better is deluded.

Posted By: JoinerPaul, the thing that totally gobsmacked me was the ritual at intersections on estate arterial roads, especially where four roads meet. When my brother explained that if four cars came to the junction within sight of each other, all would stop and the first to arrive at the junction would go, then the next to arrive, and so on. That COULD NEVER HAPPEN HERE - it would be total chaos and the junctions would be permanently piled high with wrecked cars!

LOL! So called 4-way stops are very common here (most are signposted though in Montreal). And you're right, people do tend to obey the first-to-arrive-first-to-leave ordering. The problem is when people arrive simultaneously and then there's a deadlock as no-one knows who's first. In those cases, I give priority to anyone that's turning. A two-arrival deadlock is not a big deal if they're at opposite sides of the junction and not turning. I still think mini-roundabouts are better in light traffic as they prevent the need to come to a complete halt.

Paul in Montreal.

I am obviously defending the indefendible, but I dont have a sixth gear which may be one reason. I am suprised though that being in gear would make that much difference as we probably only do it for 2-3 % of the time so to see significant differences seems strange.
It would be impossible to decide who needs a 4x4 or not regards taxing them which is one reason that the Gov havent taxed them, the other being that the people with 4x4s generally own and run the country.
It may be against the law and I know you Canadians are known for your compliance, but over here we break laws a lot - especially speed laws- so its not a reason on its own to stay in gear. Your case down the hill was probably a 2000m+ mountain and we dont have them in england. Or his brakes were dodgy.

It easy to explain why rolling down a hill in gear uses less fuel than in neutral.

In gear the weight of the car (1.5 tonnes or so) will be trying to accelerate down the hill on it's own. The engine management unit will know you have taken your foot on the throttle so will cut the fuel supply to the engine. = 99.9mpg on the read out.

If you take the car out of gear, you'll roll along and accelerate, but the engine is still running, compressing air at some where between 8:1 and 11:1 ratios. that takes a lot of energy if the momentum of the car isn't there to help it. A lot of the fuel used in an engine is getting over it's own internal resistance! One reason why BMW did away with butterfly valves in their VANOS engines - Saved 10%.

It might be a hang over from the days of carburettors. I'm not a car nut, but IIRC the fuel supply to the engine was based on engine RPM/throttle position. You can cut the main jet by easing off the throttle, but there's another jet which is designed to keep the air fuel mixture right (based on rpm). So coasting may have reduced fuel in this case as the revs will be lower.

In a modern engine all sort of improvements have been made to keep the air / fuel mixture right. So coasting in neutral doesn't work.

The question is - if you are on a gentle incline is coasting going to help? I don't think so. although it feels as if the engine is creating a pull when in gear - which slows you down, that pull is still there when in neutral. The difference - some of the downward energy is going to help compress the air in the cylinder - rather then the engine having to do it on its own. Which means the fuel that does get used is used to propel the car, not keep the engine ticking over. You'll also find the most efficient part of the rev range is somewhere after peak torque but before turbo's etc kick in. Say 1500-2000 rpm. I.e. not idling revs!

And please don't think about turning off the ignition! I know someone who tried that - and wrote his car off. You'll be suprised at how much steering and breaking assistance you lose! I had to bump start my car recently and could hardly turn the thing off the drive and using the brakes was well, hard work. Find a quiet hill and attempt it at 5 mph if you don't believe me

Simon.

The fact that you like to 'push on' and the fact that you use the gears in the way that you do is a little worrying!

Its even more important driving on country lanes, that you use the car in the right way.

I don't want to come across as rude or anything, but perhaps one of those advanced driving courses would pay dividends.

Timber

I like v much to 'press on', use the gears especially in the middle of a corner etc. Keeps me awake - and it's what Fiats are for!

Interesting reading this thread.

I think everybody should be more concerned with driving properly rather than driving efficiently. They go hand in hand, and you should never sacrifice one for the other. IAM course is very good indeed, driving test re-tests every 5 years should be introduced aswell.

All traffic lights should be switched off with immediate effect.

If you're that worried about fuel consumption - ride a motorbike! My Honda VFR400 does 45mpg no matter how you ride it, 0-60 in 4 seconds, costs £36 a year to tax, and I get free parking a minute's walk from my office :-D

Posted By: SimonHNow I'm looking up to a mile ahead. Even reading road signs round the next corner!

Blimey - Only £95 and it enables you to see round corners!! Where do I sign up!

45 mpg for a motorbike may sound reasonable against an average car, but taken that it is a single person vehicle, and weighs an eighth of a car, is worryingly inefficient.

I put it down to the fact that it's an old carbed bike that it doesnt do better. My brother's R6 is fuel injected and gets better mpg despite being a bigger engine in a heavier bike with two and a half times the horsepower :)

40-odd mpg from something that goes that quick seems good to me :)

Traffic lights have their place, I was exaggerating a bit. But I would say about 95% of the traffic lights I see could have been avoided with better road plannng. I'm not counting pedestrian crossing lights. When you're coming home at night and your progress is halted by a set of traffic lights ON A ROUNDABOUT - when there's not another car in sight - is just about the most annoying thing I've come across so far in all of my 29 years on this planet :(

Posted By: Timbertraffic calming measures need to be got rid of

why on earth?

Posted By: TimberTraffic calming and speed bumps reduce the flow of traffic, and cause stop start driving which is annoying, and causes a large increase in fuel consumption.

Hear hear. The people that implement these plans are usually clueless as to how to design a road system that is both safe and efficient. We have it even worse here - 4 way stops at every intersection or traffic lights on others that are both badly synchronized and still cycle even when it's the middle of the night, rather than defaulting to flashing amber in the main direction and flashing red on the side roads. I leave it as an exercise to the reader to figure out what this signal means :)

Paul in Montreal.

Posted By: SimonHIf it's anything like the US it means you have a lot more crashes at the lights when someone belives they can go on flashing red, and the person coming alomng the main carriageway on flashing amber T-bones them.

Got it in one :)

What's confusing is that in Quebec, a flashing green means that the green is advanced and hence you can turn across the oncoming lanes (since they're still red). In British Colombia, a flashing green means that the junction is more like a flashing amber / flashing red combination and the 1st to arrive has priority (even if they're on the side street). Confused the heck out of me when I tried to turn across a junction with a flashing green and found, to my surprise, the oncoming traffic was, well, on coming!

By the way, Montreal is the only place in North America (save for New York City) that doesn't permit right-on-red (the equivalent of left-on-red in the UK). Once you get off the island, right-on-red is allowed, except where there's signs that say otherwise. Apparently Montreal drivers "were not ready for right on red". I wrote a letter to the local paper pointing out the logical fallacy of this since right-on-red is equivalent to a four-way stop, of which there are a-plenty here. Stupid bureaucrats!

Posted By: SimonHThey reckon it would save bucket loads of fuel.

Definitely. Only problem is pedestrian crossings ... but that's a whole other issue.

Paul in Montreal.

Posted By: adwindrum
I also live in cornish country lanes and there is no way you can drive round them with their ups, downs and bends while changing gear. I wonder if this has meant I have a different style of driving? City and long haul drivers may be more used to staying in gear.

adwindrum that seems strange. Are you saying you can't be expected to change gear because of up and down hill roads and bends? Surely that what the gearbox does - allowing the engine to cope with different gradients and speeds? Are you saying you just plug along in the same gear? Maybe you need an automatic? I live on the Devon Dorset border and we have lots of small, winding lanes and steep hills. If I didn't use the gearbox I would never get anywhere.