Fair bit puzzled over mpg..
 

So.. long story short.
Came back from a two week trip to Poland.

Car is 2005 XC70, 2.5t, often producing slurping noises in the fuel tank (by the book, it's supposed to average ~25 mpg)

Now.. on the way "out" , to Poland, I didn't pay much attention to fuel consumption, other than noticing that after filling up at shell bead Dusseldorf, (e95, cheap one), tank was enough to cross the Germany and get to petrol station some 30 miles into Poland, with 15 litres still remaining in tank. That's roughly 750km/some 450-500 miles.
Fill up to brim at Orlen, again cheap e95 and .
70ltr tank wasn't enough to make it to Warsaw, 400km/250 miles away.
Strange, but.. that doesn't surprise me as much as what follows:

Return trip, I've been using e98, again from Orlen, for first 300miles, and e95 from shell for remaining 1000 miles (yes, 1300 each way).

On the piece from Warsaw to same petrol station by German border I used 30 litres..
And average for whole return leg... 32.5 mpg.

I spent whole morning yesterday looking for that missing fuel stop, it's just impossible that this car, with this engine, loaded to its absolute limit, used only 180 litres on 1300 mile leap.
Impossible.

Even onboard computer says AVG 26mpg.

But I checked. That's all the fuel I put in.

How. The. Heck. Is. This. Possible ?

:)

You're obviously selected by our space lizard overlords to sow doubt and confusion.





That's all I got.

Confused seems to be MY middle name at the moment.

The only logical explanation I got at the moment, and I'll do some searching a bit later is that Polish e98 and German petrol in general are something... Different .
I know, for example, that e95 I've been filling in Germany, had 5% bioethanol mixed in.

For now I'm trying to get over the numbers, later I'll be trying to figure out how to repeat this on day to day basis.

Cause on day to day, no matter where I fill and what fuel it is, in UK, I do run on 22-24mpg average.

Their motorways have different tarmac that makes less noise/provides slightly less rolling resistance so you'll get better economy.

I ALWAYS find my diesel cars do better MPG on the continent, partly because we are only ever doing long distances, multiple tanks of motorway work on cruise control with no town/country road driving, partly maybe heat, in summer its often warmer on the continent, diesels prefer being warm. But I think fuel quality has got something to do with it as well. In Germany/Austria/Hungary we often get 'truck' diesel, which I think has a lower cetane rating (bad), but somehow we get better mpg from it. Might be it has a lubricant in it that our mechanical fuel pump engined car likes more? Smell from exhaust is defo MORE dieselly on euro truck stop fuel.

Prevailing wind as well? Makes a huge difference even 15mph of wind tail/head wind can make a big swing in your MPG figures.

Water in fuel, could be you had some milky crappy water logged fuel that you've been using when in UK, then you've done several big full tanks of fresh fuel and used up all the water laden fuel (I get big issues with this on motorbikes, lots of water in UK fuels IME).

Hmmm... Fully logical.
But.

After return, I started "experimenting" with different brands of fuel. My average mpg was climbing, two of best being Sainsbury's super and shell 99octane. Mpg went high, as for this car. Record shown by on board computer was 26.6 mpg.
Then.. I filled premium at station with green flower.
Almost instant drop to 23.6, and after using up that tank, I struggle to bring it over 25 no matter what I fill.
So.. apart from tarmac..
Is it at all possible that European petrol has additives that help engine, with effects lasting for about 3 weeks after return to UK.

Or is it more possible that something went wrong with my engine same time I filled that premium, not necessarily caused by fuel at all.. and now it burns more..

I’ve been having this issue too with a Ford Transit.

A new EGR valve was fitted recently by a local trusted garage, but there were codes for water in fuel. I know the EGR is a separate issue, but the mechanics spotted the water in fuel errors & said its best to put a new fuel filter on… fair enough.

Previous to this (several months ago), I stopped to get fuel at a place that I wouldn’t normally go to (still a Texaco, but I rarely use it). After getting fuel, the van never seemed to run right after it, despite more fuel filter changes since then.

I’ve never been back to that fuel station again, but use a local Texaco that I’ve been using for many years for fuel. No other vehicle I drive or my family drive are getting these error codes & we all get fuel from the same place.

Its odd. I must have got a tank of water from that other garage! :confused_smile:

One thing that we can never be certain of is whether or not we get full measures of fuel. We have to trust that when a pump says that it has delivered a litre then that is what has been delivered.

Perhaps we get short measures in the UK....

Your fuel economy sounds really poor to me. My S60 has the same 2.5T B5254T2 - if I was only seeing 26.6 mpg on the trip computer after a long run I'd be worried.

Even your 32.5 mpg in Europe sounds a little low to me - I can see that on 60 mile trips around the Cotswolds, including some brief "spirited" moments, and up to 35 mpg on a steady motorway run. All my figures are from the onboard computer. I do mostly run light with only me in the car.

Last year after I bought the car, money was tight and I mostly ran on Asda petrol. I saw 28 mpg as my average, with 30-32 mpg on longer motorway runs or sticking to 50mph.

This year I've been mostly on BP standard 95. Easily 30+ on any trip, at least 32 and normally 35 on motorways. I also had a full alignment done which was needed and did help the improvement, and switched to Michelin Pilot Sport 4 tyres, which also seemed to help.

Now I've changed fuel again... E10 is here, and I've been saying to myself all year that although it's meant to be fine, I'm not going to use it. I bought BP Ultimate 97 for the first time last weekend. 55 litres added on tank 1, then 45 litres added on the way back from Exmoor on Monday night. I try to use BP wherever possible purely because they're the most convenient locally where I am in Oxfordshire.

My car used 45 litres of mixed 95/97 then, doing 320 miles of driving Saturday to Monday. First from Oxfordshire down the M5 to Exmoor, just me, then close to 200 miles over Exmoor, all fully loaded with three adult passengers and a dog. She went up Porlock hill twice, did the climb out of Lynmouth, ran flat out for an extended period on B-roads over the moors, then got me back to BP at Taunton (now just me in the car again) where I topped up. At that point the trip computer was estimating 150 miles but as there was still 25 litres left, that would have climbed pretty considerably as soon as I got back on the M5.

My overall fuel economy for the trip (Oxfordshire to Exmoor, working very hard for 200 miles over Exmoor, then back home again), was 30.6 mpg. The M5 south we were stuck in traffic for ages too which killed it, then Porlock hill was frustratingly slow both times, stuck in second with a lot of throttle and almost hearing petrol drain away. But I'm sure I could still have got over 450 miles, maybe even 500 miles, from that tank of fuel... Just wasn't safe to leave it and try though, in case I'd hit traffic on the M5 north coming home.

Result after driving 100 miles home from Taunton, at 70+ and flat out up the hill on the A417 back into the Cotswolds... the trip computer was estimating a range of 455 miles when back on the driveway.

This is very encouraging to me - back when I was on Asda petrol, I used to drive away from the forecourt being pleased to consistently see 440 miles estimated on a full tank.

I have no doubt at all that my car with me as the driver would do 500 miles on a clear motorway, with good petrol, before I really needed to worry about refilling.

…..but is you S60 manual ? It won’t be AWD…

Ahh yes I’d missed OP is AWD so maybe not such a useful comparison.

Mine is manual yes.