Have you taken action to cut your fuel bills?

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.

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?

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.

wavechange,
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.

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.

“… 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.

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 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.

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.

Fingers too quick! http://www.honestjohn.co.uk/search/?type=question&q=diesel+fuel

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.