But many modern engines have electronics that shift the ignition to the max for the fuel, so a higher octane with a 'better' fuel will give more power , in the uk they recently did dyno tests with several different cars and makes of fuel, the bp ultimate fuel in an impreza gave about 20 bhp more, while little difference in a cooking car.
mrcheerful
An update to earlier posts in this thread...
Regular readers will recall how Our Hero's Prius had been giving as high as 58-60 mpgUK during warmer days of August but that this figure declined when weather became colder and damper. There was discussion of causes, which wondered about (a) energy drained off by lights/demist/ac and (b) winter fuel mixes. A Net calculator of cruising energy demands was referenced.
This afternoon (Sat 10 Dec) I began to question whether the tyres were actually at the right pressure. They had been filled quite recently -- just before our really chill weather set in. On top of that, the Prius requires (AFAIK) higher than usual pressures:
38 psi front, 36 psi rear; this might cause faster air leakage.So I checked: 33 psi front, 31 psi rear.
After refilling, I reset the mpg gauge and, during the 10 miles home, got 62.7 mpgUK -- instead of around 51.2 mpgUK. But note that this was with the car properly warmed. I expect the longer- term average will be a few mpg lower. I'll try to post an update in a week or two.
The car also felt more nimble, more the usual EuroJap-style ride.
May I emphasise that the thinking and calculating people did was not (IMHO) wasted, as it helped put energy drain by extras into perspective. It looks like, as cars become more efficient (and probably less massive), such percentage points will become worth tracking seriously.
Meanwhile, the lesson for me was the BIG effect tyre pressure can have on fuel consumption. And how easily a drop in temperature can make tyre pressures fall. :-(
Thanks again for the discussions.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.