The gas gage is not very accurate. Unless you can verify via the trip odometer and actual gas gallons filled, then it is probably just not true.

 

I sort of noticed this too and wondered the same thing, so you're not alone. Haven't actually tried to test it though.

 

Hmm, I'll try and keep an eye on this to see if I notice anything.

 

This is actually true to some point, I overfilled almost 0.7 litres of oil and the mileage sucked real bad. Drove the car until it was 0.25 litre under full mark, top up fuel tank and my mileage was slightly higher.

 

I can't see how oil level could affect gas mileage. In piston engines if you way overfill you can get foaming, but that usually results in a blown engine. With the system an RX-8 uses I don't think there could be any foaming, and the ECU doesn't know the oil level either. Might want to do it a statistically significant number of times and be sure.

 

I don't know if this represents any kind of correlation between oil level and gas mileage, but I have a spreadsheet of my gas mileage, and every single time I get an oil change, my mileage drops about 1 mpg. After about 1000 miles or so, it goes back up to where it normally is. This never fails.

 

hmmm. now that you guys mention it, i've noticed this also and wasn't quite sure if i was being too sensitive about it... but, i guess it's not just me after all.

the last time i added oil it to get the dipstick to the full level (like the manual says to do every other fill-up), i noticed a drop in my mpg. am starting to think it might be better to add oil every 3 fill-ups instead, since the oil level on the dipstick never really gets dangerously close to low level. (it's usually about half way or more than half way between low & full every other fill-up.)

i think i'm going to do that this round and see if the mpg goes back up... let's all keep an eye on it. am very curious about this now...

 

I calculate the gas mileage after most fill ups... I've found that some tanks can be reasonable and others are terrible. I always use the same gas and don't really drive differently enough to make that much difference. (one would imagine) I'm having a difficult time understanding how there can be so much variance.

That's very interesting that you think there may be some correlation to oil level. I'll pay more attention to this, but I don't burn excessive amounts of oil. I add about 1 liter every 2500mi.

I have calculated gas mileage when on the track and it is nearly double (70-80%) that of my usual road driving. With my previous car (non rotary) the mileage would only go up by 20-30% when racing around a circuit. These things are thirsty.

 

Not following you on this one. Are you saying that you get better gas mileage on the track? You should be getting very bad mileage on a track running wide open.

 

Sorry if I was not clear. My rotary seems to use ~70%+ more gas while givin' er the goose on the track. (as compated with driving the same car on the street) Whereas my previous volkswagen only seemed to guzzle 30% more fuel while tracking the car. (over street driving)