'How much further can you go on a tank of petrol?' blog discussion

andymc29

I've been trying the Shell fuelsave fuel and I'm gaining about 30 miles per tank, which is pretty good. I just tried a tank of the new tesco fuel but only saved 30 miles, even though it's more expensive than the shell kind, so I'm refilling today at shell.

tomstickland

There is residue and sediment left behind due to impurities that can be sucked into the fuel pump and clog it (especially on older cars). The fuel is also used to help cool the fuel pump, you can even hear the fuel pump is louder on some cars as it has to work harder to suck in the fuel.

Pumps have a fine plastic mesh filter on the end of them.
I've never seen any of this residue in the the tanks I've looked in.

Bigun28

I’ve been doing this ‘hyper-economy’ driving for quite a while to drive to and from work for the past few years. Work is 15 miles away and the drive is through 2 villages, down a dual carriageway and through the country side.

I’ve got a 1998 VW Passat estate 1.9 TDI, and with normal driving, the fuel computer quotes an average mpg for a return journey of around 48-50 mpg. But go into ‘hyper-economy’ mode with gentle acceleration and braking etc and it will get an average mpg return in the early 60s, and the best yet was an average of 66 mpg for a round trip.

So for me, seeing how much more mpg I could get for gentler driving kind of got me hooked into this ‘hyper-economy’ driving.

worried_jim

I've just done 400 miles in an 1997 Astra td and managed 36mpg. Doesn't sound a lot for a diesel but I was running on 100% waste vegetable oil which cost me zero pence . I have been doing this since September last year, although not through the really cold weather but in 12 months I have spent £96 on fuel and the rest has all been free. I smile every time I drive past a filling station and shudder at the prices. I've done about 3000 miles in the last year which works out at 0.04 pence per mile. Happy Days.

YANA

tomstickland wrote: »

Pumps have a fine plastic mesh filter on the end of them.
I've never seen any of this residue in the the tanks I've looked in.

I could show you a good handful on our heap.
Most tanks will rust from the inside out, especially if they spend most of their time less than 3/8 full.
Many vehicles use plastic tanks now so don't suffer in the same way, but anyone who has a filler filter will be aware of the crud that builds up from filling up. It's not much, but after a 20, 30 or 40 years it's enough to clog the pick up filter. You'd be amazed in some cases of what can be extracated from a tank of only 10 years of age, especially if they are from a vehicle that works hard in harsh conditions.
It's in-tank pumps that run hotter when levels are low, but this shouldn't affect the life of the pump - shouldn't, but it's heat that is the enemy of all electrics!
An engine should be kept in it's torque band. That means it's as bad to use it in too low a rev range, as it is to rev it's head off. Don't accelerate too slowly, but don't try to point the headlights skyward either.

tgroom57

I'd need to know your speed on the 50 mile motorway round trip. I'm guessing you went over 56mph.
I think if you kept to 60 on the motorway section you could get it over the 300 mile mark on the tank.

I'm trying to get my daughter to keep to 60 on the motorway with the promise she'll have extra petrol in her tank if she does: so £15 would do her the round trip instead of £20.

YANA

Although speed in many ways is a simple and useful guide, it's more to do with revs, throttle opening, gearing and road type/conditions.
Religiously sticking to 60 is as bad sticking it on 70 all the way.
A steady increase to 70 when the vehicle wants to is fine, but by the same token a drop down to 50 may also be in order. Let's not forget about the traffic behind of course, we don't want to upset non MSE'ers too much!
Many cars now have 4-5" of sound proofing around the front of the floors and bulkead, not to mention all the covers underneath the bonnet and the rest of the vehicle. Modern cars are not as intrinsically quiet as many think and I reckon if we get rid of much of this soundproofing, speed and acceleration would drop and people would become more mechanically sympathetic and economy would increase. Alas the EU wouldn't agree!

peterbaker

I have the same engine as Randal but in an Audi of similar size. For the 55,000 miles I've had it, I constantly get 800 miles from 70 litres in the tank which is I think around 50mpg. I reset the trip mileometer everytime I fill up. The consumption is so predictable that I can use the trip mileometer as a second very accurate fuel guage.

My own thoughts about this kind of economy driving are that apart from a super engine (I think the 110hp TDi engine was years ahead of its time and must have launched the technology for the engine in Jeremy Clarkson's A8 when he famously drove from London to Scotland and back on a mere tankful) then modest acceleration and sensible anticipation to avoid unnecessary braking are the main key elements. Clearly the cruising speed is also a major factor and is far more noticeable in a poorly streamlined van. My 50mpg is obtained despite motorway highish (motorway) cruising speeds.

I agree with much of what tomstrickland says ... and in particular I think the cr*p in the tank is mostly an old wive's tale in 2010.

I do not however believe that rapid acceleration goes unpunished in either fuel-saving or general wear and tear terms. Unless you are talking about the very latest "fly-by-wire" technology which might moderate the demands of a heavy right foot into something the engine can efficiently handle, then it is quite likely that the efficiency of the fuel burn will be significantly reduced under 'vigorous acceleration' - look at the black smoke from many diesels overtaking on the motorway when driven aggressively.

I do however also very much agree with Martin's dilemma over traffic lights - I have 3 points to prove it from a traffic light camera on a wide dual carriageway junction on the A12 which I hadn't been through for years. Then one day I am using that route completely uneventfully then Woomph! a bright flash in the rear view mirror .... My subconscious reluctance to use the brakes momentously was significantly to blame. I was simply tailing other traffic in the usual ebb and flow except anticipating and braking less than the guy in front, and had reached only 40mph in a 50mph speed limit as they were accelerating away from me and I should either have thrown it all to the wind and kept up with them or anticipated the short fuse on the lights :mad:

Not exactly a moneysaving year or two after that because it affects your insurance premium in ways that would otherwise pay for quite some litres of fuel

PS I too have tried Shell FuelSave and believe that the current batch is probably delivering the promised 5% extra, but I do worry that Shell in particular mess with our heads with their different fuel types deliberately, and I am not convinced that they keep the composition of the fuels constant for very long after they launch a new "name".

mp80

Got a couple of cars, Honda Accord 2.2 diesel and a BMW 335d coupe.

Accord is monumentally efficient on the motorways. I drive 400-500 mile trips regularly and average 55-58 to a gallon according to trip computer. This is achieved by engine braking, anticipation in driving, and also accelerating quickly and getting into top gear as soon as possible. 60 Euro tank which is about 48 quid? (60+ quid in the UK ) It's not so good on short trips though, big diesel burns a lot when stopping and starting.

BMW is a different story, but then I drive that "enthusiastically" 35 is about right... same cost to fill.

mp80

Actually just remembering the old K reg Audi 80 1.9 TD I had ( B4 TDI engine with superb early-gen Bosch fuel injection and none of the emissions limiting crap in modern ECUs! ) used to get 70 to a gallon regularly, brilliant car and it's still going! Not sure the particulates are so good though