Discussion
Have your say nowSome good tips but I’m not sure about a couple of them.
Idling – there is a fuel penalty for restarting the engine, I wou;dn’t turn off unless I was going to be stationary for a minute or so, eg road works traffic lights, dropping someone off when they pop into a shop. If people are constantly restarting the engine it can slow traffic up when getting away, which uses more fuel overall.
Running on a low fuel tank – well maybe, but some people end up adding extra miles to get to a cheap fuel station, so its not always a gain.
Air conditioning isn’t straightforward. Above somewhere around 50mph open windows interfere with the aerodynamics so much that if there is a need for cooling, its better to use airconditioning at these higher speeds.
And I’m surprised you don’t refer to cutting out unnecessary accelerating and braking. Braking wastes momentum and therefore fuel – by far the best fuel saving in a vehicle is to take your foot off the accelerator (alt which point you use no fuel at all) as early as you can to avoid wasting fuel by braking more than you need. Its about anticipation.
Hello Ian,
Thanks for your comments. You raise several interesting points. On the issue of air conditioning, however, the jury is still out. Experts have offered crossover speeds- the point at which drag from open windows reduces fuel efficiency more than turning off air conditioning improves it – at anywhere from 40mph to 65 mph (American Society of Automotive Engineers). In practice, for most UK driving at legal speeds, except motorway driving, open windows are probably more fuel efficient.
Ward Atkinson, a US auto engineering consultant who if a frequent conference speaker on automobile air conditioning, offers 4 key points to reduce the impact of air conditioner use on fuel efficiency:
1. Use “recirculate” or “inside air” settings to cool already cooled air rather than constantly trying to cool hot outside air.
2. Turn down the fan speed as soon as a comfortably temperature is reached.
3. Open a rear window or a front and rear window to assist the air condition on a car that has been sitting in a hot sun. Close the windows and set to recirculate as soon as the car is comfortable.
4. Check and clean the car “cabin” air filter often.
Why don’t any petrol stations offer a service of checking tyre pressures and oil for you? If I knew a petrol station that offered this service, I’d be a loyal customer, as well as having improved fuel efficiency by having the correct tyre pressures all the time!
- Elaine
Elaine, they used to do this service way back in the 50’60’70s,would be nice now but, with the volume of traffic there would be queues forever,especially with the false nails and suit brigade , I used to work in a personal service petrol station and you get run off your feet just serving petrol , brilliant job though loved every minute of it
- carolYou didn’t pick up Ian’s point about braking. It’s not unusual to follow a car which has its brake lights on nearly half the time – and that’s just turning fuel into brake heat. Often this behavious results from following the car in front too closely; hang back and coast to adjust your speed – and don’t tail-gate!
- Bill Affleck
How true is the comment regarding maintaining tyres at the correct pressures.Don’t you remember how much more effort was needed to cycle along when the tyres became soft.
I now always use Nitrogen in my tyres which is much more thermally stable than air. Many tyre depots inflate with Nitrogen when supplying new tyres and also will check and top up for free.
- Roy KnightInteresting idea, Roy and one we had not heard about. We checked with the AA and while they discuss the pros and cons of filling up with nitrogen, they don’t recommend it for ordinary motoring. Here is their take on the subject. Filling tyres with nitrogen – For specialist applications only
- energyrethinking
Just a minor point re Ian baker: “… by far the best fuel saving in a vehicle is to take your foot off the accelerator (alt which point you use no fuel at all) ”
I am sure that Ian is aware that the engine is still idling, even with one’s foot off the accelerator, and is, therefore, still using fuel! I mention it merely in case someone new to driving thinks that by driving in second gear with their foot off the accelerator, they will never have to purchase any more fuel!!!!
Re the original list of tips, I agree that frequently putting a little fuel into the tank is not a real economy. There is even an element of evaporation that is exacerbated if the tank is only half-full. There is also an increased danger of running out of fuel!
- C.Brian RossGood points. How about not using the car at all if you don’t have to?
My 10 year old diesel Astra cuts the fuel if you throttle down when the revs are over 1000. It can be surprising how far you can go like that at 60.
With half a tank full, don’t you use more fuel just getting it? unless you’re lucky enough to have a competitive filling station close to your regular route. In winter I keep a full tank as a hedge against bad weather, fuel shortages, and to assist traction. Remember last year?
Have you noticed garages now charge the earth for air? You have to put it in yourself and be quick about it. I have my own foot pump and do it at home. What are the economics of a battery (cigarette lighter socket) powered air pump – must be good for the less agile.
I liked the comment about journey planning BUT as a nation we’re not good at planning and the examples given could have been better. I’d be appalled if I had to drive between the chemist and grocer. Where I live any fuel saved would be used up looking for parking.
As far as driving techniques go there is good evidence that advanced drivers have good fuel and service economy as well as being just as fast or faster overall. (we tend to wear things out less). The thing about heavy (excessive and frequent) braking is having a driving plan – among other things it means you are looking well ahead and not racing on when you’re giong to have to stop soon anyway.
And do the kids REALLY need to be driven to school? What makes the roads outside school dangerous are the school run mum! It only takes a couple to change things for the worse.
Checking tyre pressures at the petrol station is exactly the wrong thing to do. Even if you have driven only 1 mile the tyres will be warming up and the pressures increasing. Setting them to the “cold tyre pressure” when warm will then under inflate them by definition.
- Graham
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