[s-cars] Ideas to Increase mpg?

[J. Khang]

Dave,
 
- Remove the front and rear wire-mesh screens on the MAF sensor, be careful not to damage the anemometer's heated wire.
- Install a drop-in foam filter
- Renew the ignition coils and spark plug boots
- Replace spark plugs with NGKs, index if you can and gap at 0.8mm
- Decarb your cylinders. I pour in a little lubricating oil like Redex or MMO then squirt carb cleaner in before replacing the plug. Then I leave it overnight and start the car the next morning.
- Align the front wheels with minimum in-spec toe-in, don't let the technician fiddle with the toe-in to correct for uneven wear. Correct uneven wear by occasionally unmounting the tyres and swapping the inside to outside if your tyres are bi-directional
- Use energy saving tyres
- Use narrower tyres
- Don't use the AC, shut off the compressor and let in external air instead if this is comfortable
- If it's too hot and you need the AC, set the temperature to LO and regulate the temperature manually by fan speed - this reduces the amount of heating taking place within the AC system (air is heated then cooled, which costs more energy)
- If you use AC quite a bit consider using an 80C coolant thermostat, the amount of heating as explained above will be less
- Insulate the AC return pipe - this reduces the work that the compressor has to do to re-compress the refrigerant. Otherwise, the refrigerant just absorbs engine heat, which must be rejected again at the condenser.
 
- When you drive, build speed when approaching a rising slope then go up with enough throttle to just maintain or even let the speed fall back as you climb. Back off on the throttle on the other side of the hill and coast.
 
I have an automatic S6 and I can get 11.5 km/l (32-ish mpg - Imperial) on the highway at 75 mph (indicated) in 35C heat, AC on all the time.
 
Jonathan