As the price of petrol edges ever higher, can a change in driving habits use less fuel - and salve a car fan's conscience?
I'm a keen recycler, buyer of energy-saving lightbulbs and user of public transport, but when it comes to cars all my green efforts go out the window (rolled down, sunroof open). Until it started to cost an eye-watering £54 to fill my car with fuel.
Smelling salts to hand...
With petrol now well over £1 a litre, even my relatively "green" Mini is fast becoming an expensive luxury rather than a convenient mode of transport.
But proponents of a motoring technique known as "eco-driving" - who include the AA, the Energy Saving Trust and the government - claim that it will not just cut emissions of carbon dioxide, but could also improve fuel efficiency by up to 30%.
The idea is that through good maintenance, a more relaxed driving style and cutting out short trips, you can make a difference to the health of the planet - and your wallet.
Tim Shallcross, of the Institute of Advanced Motorists, says while car manufacturers have many ideas to make their products more environmentally-friendly, using smarter driving techniques can make an immediate difference.
Once at your destination, take off emptied roof boxes
"If you've got a 15-year-old Range Rover and you use these techniques, you'll save fuel today."
Tim is full of statistics that suggest a little effort can go a long way.
"Many people are going on holiday at this time of year, and they'll leave their topbox on for the entire trip. At motorway speeds, that can increase fuel consumption by 20%."
So with his encouraging words to guide me, I set out for a weekend in West Sussex.
LEG ONE: LONDON TO SUSSEX
This experiment in eco-driving is not scientific. The Magazine's budget does not run to either specialist fuel efficiency gadgetry, nor does it include one-on-one coaching from an expert.
My car has its own on-board computer, which includes an average miles per gallon setting.
Working the gears too hard and over-revving are definite no-nos
First rule of eco-driving - ditch unnecessary weight. The suitcase, beach bag, cool bag and picnic rug are weekend essentials. But I chuck out old car park tickets and receipts, and recycle the accumulated water bottles and drink cans.
Next I make sure the tyres are inflated to the correct pressure. Under-inflated tyres are not just dangerous - they create more resistance to the road and so make the car less efficient.
Stopping at a supermarket to get fuel, I obey another eco-driving edict - not to brim the tank, as this adds extra weight and reduces fuel efficiency. I pump in 35 litres (the tank holds 40). £41.26 - painful, but not as bad as before.
In the interests of science, I have decided to drive in my usual manner to Sussex, then eco-drive back to London.
Ninety minutes after leaving, we're off the dual carriageway and onto a lovely B-road.
It's a driver's dream. There are fast bends, slow bends, dips, crests. I find myself doing lots of non-eco driving - braking into bends then accelerating out. Overtaking a horse box (albeit safely) was also a bit non-eco.
We arrive at West Wittering on the coast. Before picnicking on the beach I check the car's computer - 39.2mpg to beat.
LEG TWO: SUSSEX TO LONDON
I do have one small caveat for the return leg, and that is the conditions for getting back to London are a lot more favourable than the trip down - it's later in the day and a Sunday.
Change up before 2,500rpm (petrol) or 2,000rpm (diesel)
Drive smoothly, avoiding sharp acceleration and heavy braking
Use air conditioning sparingly
Faster speeds increase fuel consumption
Drive off immediately after starting from cold
Take off roof racks and boxes when not in use
Avoid short journeys
Plan route to avoid congestion, roadworks and getting lost
Check tyre pressure is correct
Switch off engine if stuck in a jam
Source: Energy Saving Trust
With 39.2mpg to beat, we head off. The picnic bag is empty and my mother-in-law has received her gifts, so our cargo is possibly a smidgeon lighter.
The central tenet of eco-driving is to get into the higher gears sooner and not to rev the engine too hard.
At 2,500 revs a minute, I change up. And again. And again. So far so good. The road is relatively quiet, there are no speed bumps and few traffic lights.
An eco-driver has to read the road - if you can plan ahead, you won't be accelerating and braking so much, thereby saving fuel and CO2 emissions.
Sadly I am a bit poor at this aspect, and miss my turning. Doubling back wastes fuel, pumps out more greenhouse gases, and earns me some wifely derision.
For as long as I have driven, I've used the gears to slow down. But with eco-driving, the idea is to lift off the gas in a higher gear, and allow the car to lose momentum.
If you're a good eco-driver, you'll then select the right gear to smoothly move on, without coming to a halt and having to bury your right foot in the carpet to get going.
Soon, we're cruising along the A3 at a stately 60mph - 10 miles per hour under the speed limit is good for the environment and more miserly on fuel.
Apparently a car's most efficient speeds are between 45-50mph, but at that speed on a dual carriageway I would need a man with a red flag walking in front.
Even at 60mph, the car's computer relays good news. At one stage I have to blink as the read-out tells me I am achieving 48.7mpg.
The eco-driver learns to respect the power of the right pedal
I begin to think I can get through the magic 50mpg barrier. That's our house to my folks in Bristol on just two gallons of fuel.
It's not to be, of course. We get stuck in roadworks.
My eco-driving checklist says to turn the engine off if you're stationary for more than a minute. I do. I also pray that we're not here for long, as I can't make up the time lost by travelling at a fuel efficient 60mph.
As we move off, the fuel economy drops down to 47.8mpg. Then I remember another of Tim Shallcross's fuel-saving wheezes. If you lift off the gas, keeping the car in a high gear, the engine's computer will stop injecting fuel.
The Surrey hills give me some extra momentum, but the read-out remains resolutely stuck at 47.8mpg.
Even as we hit London, and the traffic builds and the red lights go against me, I do my best to brake gently, accelerate smoothly and anticipate the road ahead.
Reading the road ahead became an obsession during the trip
Even in town, with extra traffic and some frankly bonkers driving by others, I'm still on 47.8mpg.
Doing the maths in my head, I realise that eco-driving could potentially deliver a 20% improvement in fuel economy. Beat that, hybrid drivers.
Five minutes from home, my concentration lapses after coming to a gentle, fuel-efficient stop at a red light. I pull away from the lights while still in third gear and stall.
I over-cook the restart, and rev too hard. The computer clicks down to 47.0mpg. I can't get it back now, this close to home, even so I've eked out another 7.8mpg by eco-driving.
I'm doing the same trip again on Friday. I'm going to see if I can better 47.0mpg. Then I'll be well set for getting to my parents and back on half-a-tank.
Below is a selection of your comments.
I've got a competition going with my family to see who can get the best mpg, I was holding the record strong with 72.1 mpg on a trip from Southampton to Coventry. Although recently i was put to shame when a record 76mpg was acheived on a trip from Coventry to London. My tips, keep the revs low...below 2500rpm and get to high gears fast. Get behind other large cars to reduce your drag. Oh and try to cut out short trips as much as possible - they really really reduce your mpg.
I've just returned from a holiday in Devon and managed to get around 50mpg out of my diesel Citroen Picasso. I did this by avoiding exceeding the speed limit, freewheeling whenever possible (without taking risks) and keeping the air-conditioning to a minimum. Not bad for a car full of luggage and a family of four.
I drive a relatively new diesel car and have noticed a huge difference in fuel economy when "eco-driving". If I drive the car "hard" I get a little over 40mpg compared to nearly 60mpg if I drive carefully and cut out short trips. I worked out roughly how much this saves me in fuel costs a year: £500. Cutting out short "stop-start-stop-start" trips and driving at 60 instead of 70 (and 50 instead of 60) made the most noticeable difference to fuel economy. Driving at 60 in a 70 zone is extremely hard if you're not used to it but I found that starting the journey ahead of time and setting cruise control at 60 prevented the speed from creeping up.
I have been trying to eco-drive for a while now in our manual car, which is great. But I have recently got an automatic (not by choice) and find it hard to eco-drive as the car is obviously doing the thinking for me. Any ideas?
Modern multi-speed automatics, with Sport mode turned off to hold high gears as long as possible, quick Neutral selection at lights, and kickdown avoided, allow very efficient driving once they "learn" your preferred style. And you concentrate on the road, not changing gear to conserve fuel. The vari-speed automatics, found in many small cars, are even better as they have lower transmission losses. Automatics also give smoother traffic flow - the number of people who struggle to get a manual off quickly at lights and roundabouts is amazing. Don't even mention hill starts... with revving engines and burning clutches. I suspect for many "average" drivers, the automatic option would actually deliver better economy, despite the official figures. There would probably be less road rage, too, as automatics cause less stress in heavy traffic.
Paul Wood, Southampton UK
A good tip for reducing your mpg the most. When on motorways, slip stream larger vehicles. I'm an engineer and you might not know that drag opposes thrust, hence if you decrease drag you can increase thrust - or better still reduce fuel consumption. So next time you are on the motorway and happy to do 60mph, stay behind the large trucks - the airflow around them means your little motor is not subjected to same amount of wind drag as the truck is taking on the air resistance ahead of you both. All you'll be doing is being sucked along behind him and watch just how much you can save it really does benefit your wallet.
Re slip-streaming larger vehicles: I sincerely hope you don't have a family to grieve over you when you end up buried in the back of an articulated lorry. Think twice before giving advice which could lead to people doing stupid things. Secondly, I can think of nothing more boring than trying to eke out the last couple of hundred yards from a gallon of fuel. Simply get a motorbike... Half the fuel cost, half the time getting there because you're not stuck behind some idiot eco driving, twice the fun. Job done.
Keith Ingram, Cornwall
Slip streaming a lorry - that must mean sitting right up its tail gate and not obeying the two-second rule. I'm am sure that if you're two seconds behind the lorry your out of the slip stream.
I have practiced "light foot" for many years and get very good fuel consumption. However it is clear to me that the ambient air temperature, actually what the cars computer does with the data, makes a huge difference in fuel consumption as extra fuel is added to keep the catalytic converter at peak performance. What ever happened to the "lean burn" technology of the 80s? This gave lower emissions and better performance.
Terry, Newcastle upon Tyne
My husband and I used to have two cars but now we car share. Most of the time I drop him off and pick him up from work. My job allows flexi-working (eg from home) which makes the juggling act a little easier. It was tough to begin with as we had to plan around each other and there was initial teeth-grinding as one of us had to wait around. Now after two years, we wonder why we ever needed the luxury/cost of an extra car.
I tried some eco-driving recently in my 2.0 litre sports coupe and I managed to save about £25 in one day when I drove from Leicester to Heathrow to Leicester to Liverpool without filling up. Slipstreaming is the key ay 60mph.
I do all the things you say, and yes in my Renault Clio I can get 50 mpg. And lots of people just leave their air con on. Which is more economical on a hot day, having the window open which increases drag or using the air con? The other problem with driving at 50 (which I do) on a 60mph road is that people get impatient to do the extra 10mph and will overtake and squeeze in front. This just happened to me a cost me a broken windscreen from a stone chip. The other big saver is making sure your brakes aren't binding. When I stop on a very slight incline (almost flat) I always release the handbrake slightly and ensure the car rolls a bit. If not, I know to investigate.
David Croskell, Rugby
I've driven that way for years. Now starting to get the wife a little better. The easiest way to set the driving this way is to always change by 2,000 RPM, unless you're in top gear, keep speeds to max of 60 and be afraid of the brake and accelerator pedals. That way you never put your foot down. I bet you would be surprised how far you can drive without touching the brakes.
Paul Lockwood, Stowmarket
We were taught in the 60 to use the engine when slowing, ie through the gears, the problem nowadays is the clown riding your bumper. Slow down and you will be hooted at and cut up when they roar by, to brake hard at the next hold up. When approaching a hill, to speed up gently so the car climbs easier is normally stopped by speed cameras or limits.
David Gaines, London
Will it be cheaper just by switching to a hybrid? What about filling up your tank when the temperature is lowest because you get more volume - truth or myth?
Mathias Lee, Singapore
A true petrolhead will never be an eco-driver... the fast bends, slow bends, dips, crests are the whole enjoyment of driving. Watching your mpg on your car's computer, and trying to get to your parents on half a tank of fuel - where's the enjoyment in that? If that is your idea of being a petrolhead, you may as well go catch a train or coach instead, and leave the roads to people who enjoy driving instead. Cars are not just for getting from A to B.
If like me you have had a trouble with speeding, switching to eco-driving and trying to use the least amount of fuel can be almost as much of a challenge as trying to drive there in the least amount of time. Predicting traffic speeds, being in the right gear, slowing down without using your brakes or gears (when safe) and trying not to come to a full stop at junctions (unless you have to) all adds to the fun. It's now seven years since my last speeding penalty. I drive everywhere a lot slower, safer, and use a lot less fuel.
Alexander Holland, Abingdon, England
So the general population is carrying around enough junk to fill two cars, is permanently in the wrong gear, over revving and overly using the brakes and accelerator, doesn't look ahead (perhaps only as far as their bonnet or even the end of their noses), has under- and over-inflated tyres, and leave their engines running while sitting in 50 mins of stationary traffic on the M25. Do you know the really sad thing? Those of us who drive properly, simply through being enthusiastic about being a better driver and wanting to be mechanically sympathetic, have been constantly annoyed on a daily basis. We have known for years this is exactly how the majority of the population don't drive, hence the high accident rate. Never underestimate the power of stupid people in large groups.
Paul Matthews, Surrey
Why the need for a red-flag at lower speeds? You are confusing speed with progress. Maintaining 50 instead of 60 only "costs" you five minutes for every 25 miles of driving, but the fuel saving is noticeable. Also, maintaining 50/55 allows you to draft trucks. Keeping a safe threes margin behind a truck will still deliver a fuel saving - you can hear the reduction in wind noise around the car when you do it.
Chris, Norfolk, UK
Techniques such as this come under the banner of "hypermilling". Driving fuel-efficiently really can be achieved by anyone with just a little patience and forethought. My nine-year-old Skoda went from a 38mpg wallet-drainer to a 55mpg driver's dream literally overnight when I started to apply such tactics as coasting from a distance towards red lights and accelerating gently when they turn green, rather than driving fast towards them and having to apply the brakes to stop at the line. Unfortunately, aggressive drivers on roads in and around towns can become very tiresome, trying to force you to drive hard towards the red lights and blocked junctions, when in reality no time at all is lost as we all end up in the same place in the queues as if you were driving harder and wasting fuel.
Mark Rowan, Birmingham, UK
I've been hypermilling for some time now. Driving my 2.0 Mundano Diesel at a constant cruise setting of 55mph in 6th (on the M4) returns over 60mpg. I guess I'm also saving on wear & tear too e.g. brakes, tyres etc. But more than that, as a commuter it takes me no longer to get to work and by driving predominantly in the slow lane, all the nutters can overtake and I get to work totally stress-free (at the same time as the nutters).
Of course, you could have taken the train from Victoria to Chichester and then the bus (which runs from right by the railway station all the way to West Wittering). That would have well and truly beaten 47mpg.
Graybo, East Sussex, UK
I have no choice but to drive to work 25 miles each way every day. I was physically unable to drive for two months and I was much more careful when I restarted, keeping to 45-50 instead of my usual 60-70 and I noticed an immediate 9 mpg difference, which I am now maintaining. It's a daily challenge to get to around 54 mpg, although weekend driving with a family knocks me back every so often. Sad to say, it makes me feel really smug as people zoom past me at 75+ and I just smile calmly and think of the pounds I am saving each year!
Alex Thurley-Ratcliff, Winchester, UK