Insightful Trekker said:
The 1-2-5 method has the potential for maximum MPG but at a price...
There is an official HONDA publication, maybe the Service News, that specifically addresses this issue. The synchro mesh rings of MT transmissions act as mini clutches to bring the gear set in sync with the shaft speed as the gear is engaged. This eliminates gear raking when up shifting / down shifting. Skipping gears requires much more work from these parts and premature wear is predicted...
I use 1,2,5 a lot, just because it is fun. I did it in my 1992 Civic years before I got the Insight. 210,000 miles later, the synchro mesh rings are still working, so I think Honda underestimates the ruggedness of their engineering.
Case in point: My Honda dealer offered me an orientation with a Honda-trained mechanic when I bought the Civic. He told me I should never let the gas guage get below a quarter tank because the fuel pump has to work harder when it doesn't have the weight of a fuller tank to back it up. Ignoring this would require premature replacement of the fuel pump.
I always figured that gasoline has weight, and likely, my best gas mileage occurs while the gas tank is nearly empty, so I've made an art of driving until the guage is burried so deeply at E that it won't move on curves. I'm always a little disappointed in myself if I fill up with less than 10 gallons. Again, 210,000 miles and the fuel pump is still doing its job.
I always figured that my fun, excessive accelleration happens rarely enough that my fixation on the MPG guage the rest of the time makes up for it. Engines like varied driving. Enjoy blowing out the carbon now and then, and spend the rest of your time letting the MPG meter teach you how to drive to save gas.
The two worst MPG sins are:
1. Excessive top speeds. Most of your miles are spent at top speeds, so the accumulated effect is big.
2. Ignoring tire pressure. This effects every mile you drive.
Beyond that, the car will teach you the rest. A few miles of fun now and then won't do much damage to your LMPG, and much of MPG is out of your control: wind, temperature, driving surface, traffic, stop lights, hills, fuel quality, distance to destinations, rain, snow, weight of passenger, etc..