[1.9SDI]

Hello all, I own a VW Golf Estate in the UK (would that be Rabbit Stationwagon or Golf Variant overseas?). As the first wave of Fuel Duty increases has taken effect today, VAT increase on the 4th Jan and a further Fuel Duty increase later in the year, I thought it would be time to see what I could do to save fuel money by making it go further.

I drive about 10k miles per year and already follow many of the fuel saving driving techniques. Documented fuel consumption is 44MPG on a mixed cycle but I can easily achieve 53MPG and can approach 67MPG on highways at 65MPH average. I never exceed 2000RPM except in 5th gear.

I've already ordered a suspension lowering kit (aluminium body coilovers) which not only increase aerodynamic efficiency but also save weight on the steel originals. I've been trying to find lightweight lower control arms (pressed steel) and hubs (cast iron?) but no luck so far, plus there's a huge potential saving in the rear suspension system. Continuing the weight saving theme, I've dumped the spare wheel and bought a couple cans of tyre weld and a 12V air compressor. I've also bought some cheap used alloy wheels from an Audi A3 and increased pressures to 45PSI.

Planned mods after fitting the suspension upgrade is to convert to 100% biodiesel, saving me at least 25% on fuel costs. Also to continue with a few aero mods and any more weight saving mods I can easily and cheaply do. One of those will be replacing the wing mirrors with smaller DTM Cup mirrors which are about half the area of the originals. And, by careful scanning of ebay, I'd like to find some even lighter alloy wheels and cover with smooth discs, and maybe reduce the width of the tyres from 195mm to 165mm. I'd really like to know how to ease the airflow over the wipers, if anyone knows?

Also, does anyone know if it's worth swapping the hydraulic power steering to electric? The pump robs nearly 8HP under load (and a coresponding amount of fuel) and even when not in use still uses power to pressurise the system. Obviously this will put more load on the alternator but is the trade-off worthwhile? Also, on an alternator related theme, I could change the rear lights for LED versions and the headlights to 35/35HID bulbs. How much of a saving on the alternator load (and fuel) would this be?

I have a few engine mods planned - most dramatically the bio conversion. But I also want to find out if the ECU can be mapped for economy, and find out if there are more efficient fuel delivery systems available (injection system)? This is my first diesel so I'm also keen to find out if there are more efficient inlet and outlet manifolds, if anyone knows?

So, to recap, I've broken down my mod categories as follows, in priority:
1. Engine efficiency
Biodiesel conversion
ECU remapping?
Fuel delivery/manifolds?
2. Aerodynamic efficiency
Lower suspension
Smooth wheel covers
Smaller mirrors
Wiper, vent, etc mods?
3. Weight savings
Remove spare wheel
Lighter, narrower road wheels
Replace heavy components?
4. Systems refinement
Electric power steering?
High efficiency lighting?
(the question marks are those mods that I'm not sure if they are worthwhile)
Are there any other mods that are proven to be cost effective?

I'm now off to read the forum stickys so I may well end up answering my questions, but feel free to chip in and add to my list.

Cheers, Steve.