[paulgato]

Very interesting to find your postings 1.9SDi.

I have a 2002 Golf 1.9TDi Estate and I've been tweaking it over the past year or so for economy. So far I'm averaging about 75 mpg Imp overall with a mix of driving, and more on long journies.

(I found your post because I need to replace my rear shocks so I was looking at upgrading at the same time.)

My best ecomod so far has been modifying my driving style. I cruise on the motorway at 50mph and I find the mpg starts to drop off dramatically even at 55mph.

Next best thing was to keep the engine temperature nice and warm. I totally block the entire grille in winter and almost totally block it in summer. A thermostat change was also required but in winter the engine just doesn't get up to temperature, and that impacts mpg. (The 'idiot guage' on the dash is designed to show '90' at any temperature between about 75 and 107 degrees, but below 90 degrees it doesn't run efficiently.)

One tip I can give you is to replace the gearbox oil. VW say you never need to but after 150k miles I decided to do it anyway. I got the right stuff from VW, a small tube of Molyslip gearbox additive (from Halfords) and got my mechanic to do the change. Once up on the ramp it took him ten minutes and he charged me £15 labour. The difference was immediate and obvious. The car clearly rolled much better - especially when coasting in neutral - and mpg (as displayed on the dash) was up by a full 5%.

I use low rolling resistance tyres and pump them up to the maximum allowed on the side wall, which is 51 psi. I will probably drop the rears back down to 45 or so but keep the fronts at 51. I find the car handles way better: steering is lighter, the car doesn't 'wallow' into corners and I've also found that it maintains speed much better when going round roundabouts and so on. I use the stock alloys and 165/65 R15's.

I also use BP Ultimate and that helps mpg a lot - pays for itself anyway. I've never tried it but I suspect that using standard diesel and adding Miller's additive/cetane booster would produce similar mpg gains at a lower cost. Millers does not improve mpg when used with BP Ultimate, but using 1 part acetone to 1000 parts diesel improves mpg by a couple of percent.

Not sure what else to add right now but if I think of anything I'll post again. Did you ever get rid of the hydraulic steering gear? Having harder tyres is always going to help as steering is so much lighter, but Golfs have always been notorious for having heavy steering. Not sure I would want to do without. I had a N/A Astra 1.7 diesel with no power steering and that was fine, but Golfs, ...nooo...!

I'm currently experimenting with engine remapping but the results are not encouraging so far. My guess is that if you normally drive slowly anyway - drive for economy rather for speed - then the economy gains with remapping will not impress, but if you are frustrated with lack of power and so tend to thrash the engine regularly, a remap with more torque can result in a more relaxed driving style and so can save fuel. But that's just a theory. I'll persevere with remapping for a while and see if I can get some gains that way. It might be the first remap was not quite right and they need to do a bit of tweaking.

I regularly drive in 5th gear at tickover speed in 30mph zones - i.e. 850 RPM and 26/27mph (traffic allowing). On the flat the engine is nice and smooth at that speed and the mpg meter goes way off the scale and pegs at 99.9mpg average. (Oh, but before I changed a failed alternator the engine was rougher at that speed and I was getting (showing on dash) more like 95mpg average at 27mph. Turned out the alternator pulley freewheel was stuck (didn't even know there was a freewheel pulley!) causing the rough idling and lower mpg at tickover.)

(By the way, my dash mpg gauge is about 7% optimistic. Useful for before-mod/after-mod comparisons though.)

I thought about ditching the spare wheel but decided against. I lost a tyre in a blizzard one dark night on a country lane a couple of years back, and without having a spare I would have been stuck. The RAC would have been 'snowed under' (ha ha) that night as it had just started snowing heavily and they would have taken hours to get to me. The tyre had ripped right away from the rim so tyreweld would have been useless. Nice idea but no, I'm going to stick with a proper spare (I also carry a breaker bar with wheel nut socket, a pair of wheel chocks, a jack, a foot pump and a can of diesel.) Every little helps but the maximum possible theoretical fuel saving from leaving a spare wheel out is the proportion of the total vehicle weight that the spare wheel represents. That's maybe 1%. But that saving would only apply to acceleration. At constant speed, friction and air resistance play a larger part than weight so ditching the spare tyre will save maybe 1/2% on fuel - or about a quarter of a mile per gallon. Now, running on a nearly empty tank most of the time could save a full 2% in fuel. My dilemma is that it is much easier to MEASURE mpg if I fill to the brim each time.