/ Money, Motoring

Have you taken action to cut your fuel bills?

Angry man on fuel gage

Running a car isn’t cheap. Once you’ve paid for the vehicle itself, along with car insurance and tax, there’s the not so small issue of fuelling it. Have you taken any steps to make your fuel go further?

As a car journalist, covering many miles at the wheel of a car every week is part of my job. It’s important for the Which? Cars team to spend enough time driving each test car on a wide range of roads and traffic conditions, so that we can include the pros and cons of each in our reviews. And that means spending a lot of money on fuel.

That’s not done without thought, though. Whenever possible I’ll drive to the cheapest garage in the area to buy a tankful. I won’t rack up extra miles by going out of my way to use a cheaper filling station, but I will plan ahead and fill up in cheaper spots – Surrey is pricier than south east London, so I’ll stop on the way through.

Save fuel by driving more efficiently

When it comes to driving my own car, I’ve become far more conscious of the fuel economy I’m achieving in the past few years. I keep the boot as empty as possible, and check tyre pressures regularly.

In general my 1.2 petrol Renault Modus is quite frugal – it averages 45-50mpg. But that little engine struggles and has to be worked hard at motorway speed. And that means it drinks far more fuel: around 35mpg at 70mph, compared with 55mpg at 56mph.

So when I had to make twice weekly trips around the M25 three weeks in a row, I soon found myself pulling into the slow lane to stop the fuel gauge dipping quite so quickly. Driving slower than most of the other traffic around me was far more demanding, and at times extremely scary, especially when HGVs pulled up close behind wanting me to speed up rather than make them change lanes to overtake me.

I persevered, but only for the sake of my bank balance. If I’d not been concerned about the cost of fuel, I would have been sorely tempted to speed up so I’d have to make far fewer lane changes and speed past the juggernauts rather than have to dice with them.

Have you taken any measures to cut your fuel consumption, or reduced the number of miles you cover to save money?


Since I retired I have been able to plan my driving to visit two or three places rather than making separate trips. That can save a lot of time, not just fuel. I share transport with one or two friends if we are travelling to the same meetings.

Often I drive at 65 mph on motorways, which saves fuel. I have always avoided driving at busy times if possible, though safety and avoiding stress are the main reasons. My diesel car averaged 55 mpg over winter and will do 60 mpg when the weather is warmer.

Nigel Soames says:
26 March 2014

I live in France where the motorway speed limit is 130km/h (80mph). At that speed my petrol just evaporates. I now drive at 100km/h (around 60mph) and it seems to last for ever… There is a “sweet spot” at around 55mph where engines are most efficient.

I actually find it less stressful driving a bit slower. You just have to allow more time for getting there!

Andy Sharp says:
26 March 2014

Happy for you to drive at 55-60 in France; please stay there to avoid clogging up our roads with your mobile traffic obstruction that probably causes lorries to over take you, thus causing further reductions in available lanes for the rest of us.

Nigel says:
26 May 2014

Lorries mostly do around 90km/h here so no, they do not need to overtake me.

Have you always been this unpleasant or is it just when you sit at your computer screen?

Rosie says:
26 March 2014

We’ve had no choice, or we wouldn’t be able to pay for essential bills and food. So my partner has to sleep on the floor of his elderly parents’ lounge 1-2 nights every week in order to cut down the fueld bill (despite him being middle aged himself, so not the best thing for his health on an ongoing basis!). Moving from this area to the more expensive area his company relocated him to is not an option (and especially after they had previously relocated their workforce to this area from another area before that!).
If the time comes when my partner can no longer sleep on his elderly parents’ floor, or petrol prices go up again (while our net income is continually going down), the backup plan is that he will have to keep a sleeping bag in the office ….!
But, of course, “We”re all in this together”!

You’ve presented a good reason to make sure that you buy a car fit for purpose. A R Modus is strictly a city car. Once you’re on open roads its pathetic engine doesn’t have the grunt to cruise frugally at the speed limit. For driving on open roads you are far better off with a 1.6 l diesel than a 1.2 l petrol and in town it will be just as frugal.

Always choose good tyres too. They may be a bit more expensive, but the correct tyre will last thousands of miles longer, provide better consumption and be quieter. They’ll pay for the additional cost.

I’m lucky to have a couple of outlets nearby that sell autogas (LPG). My essentially petrol 1.4 Astra which also runs on LPG costs in fuel 10p per mile to run with LPG at 71p per liter. And that’s a normal everyday urban cycle. I get even better mileage on a long run.
Better than the best smelly, noisy, injector clogging. particulate filter clogging MOT failing diesel.
Can’t understand why LPG didn’t take off better.

For LPG to be a success, it would need to be much more widely available than it currently is in the UK.

I agree with Wavechange. The government have shown little interest in encouraging LPG conversions. Look at what they are doing for electric cars by subsidising the cost of new cars, heavily subsidising the installation of charging points (including private charging points outside your own home), and then look at what they have done for LPG. It’s obvious why LPG is not popular.

I can see that one day electric vehicles will become a sensible choice, but until storage and/or portable generation makes a technological leap, conventional engines have the day. Likewise with LPG: if the government subsidised the conversion to LPG and installation of LPG refuelling points at every garage, then we would probably convert.

I agree with Terfar about electric vehicles. Electric vehicles are not yet a sensible choice for most people and perhaps subsidising them is as flawed as continuing to cover the UK with wind generators. Battery technology in laptops and other mobile devices has improved a great deal in the past decade and hopefully the same will happen with electric vehicles.

Electric car manufacturers have focused on high performance vehicles, but when limited by current battery technology, perhaps it would be better to produce city cars with a top speed of 40 mph. These could be attractive for families with two cars. Modern small diesel engines are economical and much cleaner than their predecessors, but the danger is that the DPF will block up if just used at low speed round town. Small electric or LPG cars seem good choices for city use.

When I bought my first diesel car I carried a spare can of fuel on longer journeys because many garages did not stock diesel. Presumably someone maintains a current list of LPG filling stations online, making it easy for Chris and others to plan their travel.

I’d agree that more LPG outlets would be useful, but really it’s a bit of a catch 22 situation, people won’t convert to LPG because there are fewer outlets and there are fewer outlets because not enough people convert, and create demand.
In the early days there was a Government subsidy on conversion but clearly not big enough.
I’m OK locally because there are a couple of LPG outlets nearby, but yes I would have to “fuel plan” longer travel. However even then it’s not the end of the world because the car runs just fine on petrol too, seamlessly at the flick of a switch. Fill both petrol and LPG tanks and I’m good for a total of about 600 to 700 miles.

I agree about noisy, smelly diesels with higher repair costs and expensive particulate filters prone to clogging which is why even though they tend to be quite good on fuel I don’t really like them much.
I did do some calculations when looking for a car with good economy. I found that a lowish mileage petrol car bought then converted to LPG worked out about the same total cost as an equivalent sized diesel, so being someone who prefers a petrol engine car which is what a LPG converted car essentially still is it was possible to find something actually more economical on fuel cost than a diesel, and of course without the diesel drawbacks. Drawbacks at least as I perceive them to be.

I’ve had two LPG cars now very much enjoy the economy without the pitfalls. I’m not planning on changing back to pure petrol or to diesel while I can still get LPG locally, and electric has a long long way to go before that becomes viable.

I presume that the subsidy on LPG conversions was in the days when LPG was a much cleaner fuel than petrol and diesel. If LPG was widely available, the government would probably tax LPG heavily. 🙁

I think you are being a little unfair about diesel vehicles, Chris. The old ones are undoubtedly smelly but not the newer ones with DPFs. Yes DPFs can block, but that’s generally because people ignore advice that they are unsuitable for protracted urban driving and fail to heed the warning of the need to do a longer journey. My diesel car does 600-700 miles without the need for two tanks, and much of my driving is on uncontested roads, ideal for the DPF to do its regeneration business.

NukeThemAll says:
17 April 2014

Chris, as Wavechange says, modern diesel cars with DPFs are anything other than noisy and smelly. Try driving, say, a diesel VW Golf or one of the bigger-engined Mercedes and you’d be amazed at how smooth and quiet modern diesels are, with the bonus of huge range and lovely low-down torque, so well-suited to today’s 7-8-9-speed auto boxes.

One factor which many people neglect when trying to work out the economics of diesel v petrol v LPG is the trade-in value – if you keep your car for, say, less than 5 years, this can be an important input, especially for larger cars where petrol power is less popular.

I have taken an extremely effective measure to reduce my fuel bills: I got a job with a fuel card 🙂

Prior to that, I cut my fuel bills by selling the car and commuting by train and Brompton folding bike.

I am now on my seventh Volvo, the fourth large estate. The previous one was a V70 2.4T auto (petrol), I averaged a bit under 30mpg. My father-in-law managed nearly that in a 4 litre auto XJS, he only got 1mpg better out of an Accord Aerodeck! It’s all in the driving style, and the first step is to care (and have a meter that shows you instantaneous and average fuel consumption in the dash…)

I’ve never met anyone who has saved money by trading to a more fuel-efficient car, because in the end it’s usually cheaper to keep the car you have than change it, however bad it is, but I am sure there will be people who have saved that way. I have had a car remapped for greater economy, and I have bought a diesel car for better economy. My current V70 2.4 D5 auto returns just shy of 40mpg average, aircon always on, all kinds of driving, 650 miles per fill. That is OK for me, and if I ever save enough to retire I will be driving a little Honda Jazz instead.

I’ve recently ordered a new Volvo XC70 D5 auto, though, which shows that economy is not my top consideration.Comfort, followed by safety toys, followed by economy. Here’s an interesting thing though: the company and fleet market is so dominant in the UK even now, that every manufacturer is still driving down emissions to meet income tax benefit in kind bands and the like. The new car has a 215bhp engine and better economy than the old, with a mere 163!

NukeThemAll says:
16 April 2014

The basic laws of physics tell us that air resistance for ‘turbulent flow’ (ie for cars at realistic speeds) goes like speed squared. Thus the slower you go the more economical your car is: there is no magical ‘sweet spot’ provided that you use the gears sensibly (which might mean travelling at 30 mph in, say, 3rd gear).

Yes, it would be very, very economical to travel around the M25 at a steady 20 mph. It would also be totally, utterly anti-social to be a mobile road obstacle – and probably illegal. Travelling on a motorway at speeds lower than HGVs or caravans/trailers (limited to 60 mph) is sheer lunacy, for such obvious reasons that if you don’t know what they are, you really, really need to hand in your licence. Right Now. Similarly, doing 30 mph on a clear, unrestricted road isn’t going to be welcomed by other road users who haven’t got all day to get where they’re going and will likely precipitate risky overtaking manoeuvres.

It’s for these reasons that fuel economy needs to be interpreted with common sense. Your driving style **will** likely be a huge factor, but please, not at the expense of frustrating other road users unnecessarily.

“… it would be very, very economical to travel around the M25 at a steady 20 mph”.

Whilst you are right about the effect of air resistance on fuel economy, you cannot deduce that slower speeds are therefore always more fuel efficient.

What you are ignoring is that, for example, driving at 20mph in the optimum gear actually takes twice as long as driving at 40mph in the optimum gear. As well as the energy cost of moving from A to B, cars have overheads that are in direct proportion to the time in operation. Engine friction – even when idling – uses fuel, so do headlights, air conditioning, oil pump, alternator losses, cooling fan, etc., and these loads are constants or at least to not follow the speed**2 rule.

It also ignores that the British terrain rarely allows one to drive at a steady state. Attempting to drive along a hilly road at 20 mph doesn’t allow the car to build any momentum when the engine is able to run efficiently. The first slight incline will involve a down-shift and yet more fuel being burnt, whereas taking a hill at a reasonable speed could enable the engine to stay in a more efficient gear.

As a general rule it is most economical to drive in top gear at low engine revs.

NukeThemAll says:
17 April 2014

The losses which are speed-independent are generally small compared to the effect of air resistance (at ‘normal’ speeds) and the laws of physics for the energy expended going up hills are independent of speed, neglecting air resistance. However, yes, it would take more skill to drive a car economically because of the need to change gear at appropriate times.

So, no, it is NOT more economical to always drive in top gear. Yes, you should aim for lower engine revs, but this can be in the lower gears. For cars with onboard fuel economy readouts, you can (using common sense if circumstances permit!) try this out for yourself. I was once caught in a huge amount of slow-moving (30 mph) but very-steady-speed traffic on the M11, for many miles. My auto-gearbox car knows what it needs to do gear-wise. The fuel consumption read-out demonstrated the point beautifully……

I run two diesel Mercedes, a 3.5 and a 7.5 tonne truck, also both diesel. I am lucky in having access to pretty much unlimited quantities of used cooking oil and am looking at getting a bio-converter. These seem to be available from about £500 and with free oil it appears, if you believe the figures, you can make diesel for about 20-30p/litre and use it legally up to 2500l/yr. Whilst this is not enough for all we use as a household a saving of over £2000 in the first year and more in subsequent years seems to make sense. My truck only does about 15MPG but the mercs do well over 40 on average (both E220CDi Estates) so if they’ll be happy on it this will bring our costs down colossally, more than any economical driving tricks.

On a slightly different note a couple of months ago I filled one of the cars up at a BP station instead of my usual ASDA. Imagine my surprise when after about half a tank I noticed an extra 5MPG approx. I filled at BP the next time to see if it persisted and it did, so I went back to ASDA for the next fill in case it was nothing to do with the fuel. The consumption stayed up, so I filled at ASDA again, but this time the consumption started to fall again. I let the car get almost empty and went back to BP and within a couple of hundred miles I’d got the benefit back. I’ve now done several thousand miles on BP and it’s stayed up. The 2-3p/l cost seems well worth while.

I have had consistently better mileage from both BP and Shell diesel and hesitate to use anything else. This is reported on by “Honest John”.

I have not found any difference in fuel economy using either Shell or BP diesel. I remember reading that a difference will only be seen after several fill-ups, which sounds like unscientific marketing hype to me.

The difficulty in making these comparisons is consistency of driving and journey types – not possible in a short period of time. I have recorded consumption over several years – just a routine when I fill up. I don’t know where “unscientific marketing hype” has come from – these are just individual experiences and I am certainly not promoting BP or Shell.

The other criticism sometimes made about cheap fuels is that they can contribute to various engine problems such as blockage of injectors. I have never had any problems and I don’t know one person who regularly uses supermarket fuels that has.

NukeThemAll says:
28 May 2014

I have never seen **any** evidence for the advantages of ‘super fuels’ that would withstand even the most basic scientific peer review. As others have said, there are many factors which affect fuel economy (and ‘injector blockage’) and thus evidence based on a ‘few journeys’ or sporadic use is essentially worthless.

It’s this basic lack of any scientific understanding which leaves so many people vulnerable to the wild claims of the marketing people, which are often only just within the law (and sometimes not). Look for words like ‘up to’ and ‘may’ and other weasel words/phrases. For some excellent examples of the misuse of ‘science’ I would totally recommend Ben Goldacre’s book ‘Bad Science’, a book which should be on the reading list for every school.

Me neither. If there was any concrete evidence that ‘super fuels’ work, then most of us would be using them.

In absence of nowt but hearsay and flimsiest of evidence that’s easily refutable, I believe that they are a waste of money.

Perhaps Which? would conduct a real trial for us. That means using real drivers out on real roads in identical cars following the same routes over many journeys to try to even out traffic and driving anomalies. Very difficult. But ‘lab testing’ on rolling roads just doesn’t cut the ice.

I recommend Goldacre’s book too, but what I think we really need is a TV series that focuses on current advertising and marketing. Consumers need to develop critical thinking skills, which will help make them aware that advertising is often based on misrepresentation, with the Advertising Standards Authority dealing with only the worst examples.

I’m not going to believe anything that a motoring journalist has to say on the matter, unless they can cite references to proper scientific studies, hopefully independent of industrial funding and peer reviewed.

Anecdotal evidence bedevils those making choices. Who do you believe and do they have substantive evidence? You have to start somewhere. I give a link here that offers some views. But others may have different knowledge and experiences. One issue is the additives in fuel, and their qualities.

I’ve looked at most of the relevant posts on that page and the only honest thing to say is that it’s all hearsay.There’s not a concrete piece of evidence proving the super fuels are better.

If you do find any obvious errors on HJ’s website, let him know and it will be corrected. I can say that from experience. But, as I have said, I don’t see journalism as a serious source of information.