Quote:
Originally Posted by wbcooksey
Does anyone know if there is info out there on optimal speed for optimal gas mileage for the R18 engine. I did a brief thread search and found lots of people reporting their own gas mileage, but couldn’t find anything much else.
We know that that slowing down improves gas mileage, but is there a *reasonable* cruising speed (other than zero!) that maximizes fuel usage? Are there any charts/graphs/data out there they says something like “best gas mileage is at 59 mph on flat terrain”, or something similar?
If not, then it sounds like an interesting project…graph gas mileage at various speeds and see what the curve does.
William
07 Civic EX + 03 Pilot
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While I can't definitively tell you this on the R18 since I've got the K20, I would put money that you'd see the best MPG at whatever minimum speed you can drive in your lowest gear, probably about 35-45 MPH. I don't ever get more than a mile or two where I get to cruise at those speeds but when I do I usually see 42-48 MPG in my Si. In my '05 CR-V the best MPG on a flat is achieved just over 40 MPH when the automatic transmission shifts into 5th and locks up the torque converter. In a higher gear you lose more efficiency to friction and pumping losses, and at a higher speed you spend more energy overcoming air resistance. Again, I'd bet you see these two curves cross between 35 and 45 mph.