Wednesday, 5 December 2012

Make Your Car More Efficient

Fuel is soooo expensive these days, or rather the huge amount of tax on it is. It's the major price of car ownership, and if you're like me living in the country, it may well be a necessity too.

Fortunately today, the UK's chancellor decided once again to put off the 3p rise in fuel duty he had planned to introduce next month, but that won't happen forever. As sure as eggs is eggs, fuel prices are going to go up again some time soon.

On the plus side, modern cars get ever more efficient, but if you can't afford to change your car right now, what do you do?

You can actually make your car more efficient without having to learn one end of a spanner from the other. Here are a few very basic tips to help you save.


Many brands now offer energy saving tyres. Are they any good? Absolutely. I've tried a couple of different makes, and yes, they definitely made a difference. For them to work best, you do need them on all 4 wheels though. On my car, I replaced them 2 at a time, and after the first 2, I saw slightly more than a 1 mpg difference, but with 4, this increased to 5 mpg. A nice saving.

I currently use Michelin energy savers which last very well too. There's still 4mm of tread left after 15,000 miles by which time other previous brands I've used would have been nearly bald.

One more thing, make sure you check your tyre pressures are correct at least weekly and keep them pumped up. Too low a pressure is bad for your tyre's health as well as fuel economy. Some people even pump them up a bit more and claim a difference, but there may be safety aspects to consider here so I can't recommend that.

2.Use an independant

I realise that energy saving tyres are more expensive, but as everyone jumps on the bandwagon, prices are now coming down. Last year most large tyre fitter chains charged £100 or more per tyre for michelin energy savers, but I was able to source them for £85 each fitted, and that's for quite a large tyre size (205/55/R16). This year, having had a quick look at google shopping, the cheapest rate is now £63 (before fitting) for the same tyres at another local, independent fitter. Most major chains are charging around £90 fitted, so it pays to stay away from the chains.

This also applies to servicing. The local Renault dealer charges £90 an hour for labour, but I take it to a bloke round the corner who charges me £40 an hour. I know, I know, I'm lucky I've found someone I can trust because I already do a lot of my own maintenance and therefore am probably a lot harder to con than your average joe. 

3.Check your oil

Click for Attribution
All oil is not the same, and you may actually be using the wrong grade. I noticed this a while ago when buying some oil to service my car. I looked in the handbook and it suggested several different grades for different environments. Your handbook is probably the same. The recommended oil will be thicker for a colder climate, and thinner for somewhere more sunny. Being in the UK we get quite a mix of weather, and there was an overlap, so I rang my local main dealer to check which one would be most suitable.

He told me the grade Renault recommend for my car was 5W40, then of course I went elsewhere to buy the oil more cheaply. I rang round several motor factors for prices and found that they all thought I should be using 10W40. I rang the dealer again to check and he was adamant about the correct grade. 10W40 wouldn't protect my engine as well from a cold start, and being a main dealer they had enough manufacturer data on file to know this as fact.

OK, 5W40 it is then. The lesson being, double check with the manufacturer/main dealer. In this case, the thinner oil would work better and make my car more efficient from cold. Also, keep your oil at the top end of the dipstick reading, it's much better for the engine both in terms of wear and performance. In the picture above, although it reads "minimum" it's still far too low. Should a driver come across a steep hill or camber, or drive more "enthusiastically", this level of oil will not suffice.

4.Change your oil

All oil is not the same, EVEN when it's supposedly the same grade.  Through several years experience working on old bangers and classic cars, I've used various different oils. I've used cheaper oil and changed it more often, I've used recommended oils and I've used expensive stuff that claimed more horsepower and mpg. I've found that one brand, although expensive, actually delivers on it's promises, and that is Mobil 1.

I know this for a fact, having used it previously in an engine that I had to repeatedly change the head gasket on, so I've seen the inside workings, before and after using this brand. The difference was quite remarkable.

Currently, I run a tired old turbo-diesel and a few weeks after I bought it, I changed the oil over to Mobil 1. It runs better and gives measurably more mpg as a result.

Of course Mobil 1 is very expensive at most places, but if you look around you will find places where it's only slightly more than other oils. I get mine from Costco for £30, a saving of £20 compared with some outlets. Elsewhere, most motor factors sell own brand oil for about £25. I used that once, and went straight back to Mobil on the following oil change, which I did early.

5. Change your Driving Style 

You may have read a few blog posts before regarding this, but many of them miss some crucial details. I'll get the obvious stuff out of the way first.
  1. The harder you accelerate, the more fuel you will use
  2. Keep more distance between you and the car in front, that way you won't need to brake as much and as often, therefore you won't need to accelerate as much, (see point 1)
When driving down hill, some people knock the car out of gear thinking this saves fuel. In older cars it did, but many cars built from the year 2000 on, will completely cut the fuelling above 1,000 revs, if you take your foot of the gas pedal, so the engine actually uses ZERO fuel in this instance. If you have a trip computer that gives a fuel consumption read out, you can check this. In fact, having a trip computer that does this can really help, as you can use it to determine the fuel economy sweet spot for your car, and this will help you make major fuel savings. Here's how:

Find a continuous piece of level road such as a motorway or freeway (so you don't have to stop). Get to and stay at a constant speed, such as 50 mph, (using top gear of course). Now you're moving at that constant speed, check the trip computer for your mpg. If yours doesn't have an instantaneous readout, then reset it, and drive for a mile, then check it.

Now change your speed, to say, 55 mph and repeat. If your fuel economy is better, change your speed to 60 mph and do it again. If it's worse, try 45 mph. This way you can home in on the absolute best speed for your car's economy. For most cars it's somewhere between the 45 and 65 mark. 

You can do the same for urban areas as well (but use a more suitable road). For example, does your car perform better at 30 mph in 4th, 5th or 6th gear?? The figures you get from this may not always be what you expect, so it can make a significant difference to your fuel bill.

6. Check your Thermostat

Thermostats are not the most reliable of devices, but they rarely fail in a shut position, so people often don't notice. Why am I mentioning this? Simply because an engine works best at it's optimum temperature. The whole point of the thermostat is to prevent the cooling system coming into force until the engine has warmed up, by preventing the coolant from circulating until that temperature is reached.

And you wouldn't believe how much more inefficient a car is before it gets up to temperature. Modern cars are also designed to be used in a variety of climates, so the cooling system often has some spare capacity, particularly if you live in a moderate to cooler climate.

You can usually tell if you need to do something by watching the temperature gauge. For example, if the needle barely makes it off it's stop, the coolant level is fine, and the heater fan is always cold, then there's a fair chance the thermostat isn't doing it's job properly.

Replacing a thermostat is quite an easy job on most cars, so you could do it yourself, (only when the engine is cold, don;t burn yourself!), or if you pay for this, it shouldn't be too expensive. The part itself is cheap too. However, there will be times when perhaps this is not entirely the case.

I used to have a V6 where the thermostat was situated right in the middle of the vee. Unlike a 4 cylinder engine, this was an absolute pain to get to, so instead, I resorted to cardboard. I stuffed a section down the front of the radiator, effectively blocking off half of it, then over the next couple of weeks kept a hawk's eye on the temperature gauge to make sure it didn't head too far north.

Overheating an engine is the last thing you want to do as it brings many headaches, non of which are cheap. If you see the temperature getting too hot, stop and remove the cardboard. It's much better to use a little more fuel than blow the head gasket. Trust me. I've replaced a few head gaskets, and although it saves me a ton of cash, it's always the most awkward, knuckle bruising job.


So there we are. This is what I do to my car, and the results speak for themselves.

As I'm sure you know, most people have great trouble achieving the fuel figures that manufacturers give, let alone exceeding them. In my case, Renault quote my year 2000 phase 1 Laguna 1.9TD (it's the model before the one shown at the top of the page), as having a combined cycle economy of 47 mpg. Measuring this as accurately as I can using the tank full to tank full method, I get a verified 55 mpg.

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