This site has been interesting. Lots of ideas and nice practical cases.
I drive with Opel Astra Caravan 1.6 16v 2001 and at the moment my last year fuel consumption is 5.94 l / 100km. (39.6 MPG)
At the moment the temperature is about -30 C (-22F) and the best way to keep fuel consumption low is to drive with bicycle.
These are my modifications at the moment:
- motor block heater (must be here)
- Dual xenon headlights
- LED daytime running lights
- some other LED bulbs
- higher tyre pressures
- internat grill block
- 0W-40 motor oils
- Scangauge II
- thin line windshield wipers
- often bicyle in the trunk
Next likely mods:
- 0W-30 "fuel economy" motoroil
- low viscosity full synthetic ATF fluid (manual gearbox)
I have though about these (some more and some less):
- temperature compensated plug in battery charger
- bigger alternator pulley
- ride height mod ? lower ? adjustable ? (need higher in the winters... "hillamaasturi")
- aerodynamically cleaner underside of the car
- rear wheel skirts
- smoother wheel covers
- outer grill block (active or passive)
- all bulbs to ledbulbs (not xenon headlights)
- roof rack removal (longitudinal)
- small (boat tail style) wing back of the car
- alternator removal (just quick belt removal)
- bigger battery capacity (needed if alternator is off)
- electromagnetic alternator clutch
- better battery technic (AGM ?)
- internal radio antenna
- smaller side mirrors
- some small aerodynamical mods
- powersteering delete (not legal
... but could burn the fuse
)
- removeable boat tale bicycle rack to hook
- in case of total motor downfall --> 1.2 liter motor
- in case of total gearbox downfall --> longer geared gearbox
i think that was most of the ideas ...