Did some experimentation with this last tank of gas in my car... Still got some more to do to make it more 'valid' data (that whole multi-sampling thing). It's a 2011 Toyota Camry with ~6K miles on it, 'rated' 33MPG highway (which is where I do a fair chunk of my driving).
While I started out with a 1/4 tank of gas, I only really applied it all after the idiot light came on, I'm a mile watcher, comparing needle to trip odo regularly and religiously. So this has some
merit, even though its really only a single 'event'. After the idiot light appears (~1/8 tank), its good for about 40 miles with my normal driving style before things get scary (bad side of E).
I had to run all over BFE today, and normally, I would have had to gas up LONG before I did, but I thought about a few things we were discussing, and applied what I could to see what would come of it.
1 - Keeping raw speed down. Kept it below 65, even in the 70 zones. Was running more like 60. If you were one of the people that flew past me glaring, kiss my #@%, at least I was in the right lane!
2 - Keeping engine RPM down. Went to as high of a gear as quickly as possible.
A - From a dead stop, only very short acceleration hits on 1st and 2nd gear (fair throttle, but limiting to ~3K RPM).
B - 3rd was a little more lax on the throttle, and shifted out at ~2500 RPM.
C - 4th was never allowed more than the throttle being cracked open, and limited to 2000 RPM.
D - 5th and 6th (except where I was forced to bring the speed up due to traffic conditions) were also kept cracked at most, and target RPM was always less
than 2000. I started out trying my 'out-the-hat' 1200 RPM, but this is down just a touch too far on the torque curve to be practical. Car was also groaning. So I upped it little by little until I found the lowest RPM that didn't squawk. Turned out to be ~1400 RPM. Tried my best to stay in the 1400-1600 range for a majority of the 'test'.
3 - Drafting. While I was only presented the opportunity twice, but they were both for decent runs, and I slid in as good as I could get without freaking the truckers out. I guess it's dangerous, but it's also damn appealing! The closer you get, the better the savings. I hung out at about the 50 ft mark @ 60 MPH-ish which works out to something like 20% savings IIRC (according to mythbusters test...). I probably got in all of about 20 miles collectively under draft conditions.
4 - Pulse and Glide. While the pulse part was minimal, I did a lot of coasting anywhere there was a hill, to keep engine speed down that much further. Did this countless times during my adventure today.
My round trip was on the order of ~100 miles, and the idiot light came on about 25 miles in. By fairly repeatable math, I would have had to refuel just after leaving my furthest destination, ~65 mile mark. That's when the needle looks as scary as I'll ever let it.
The results of applying the above however are rather astounding, and even more so because they only were applied to the last 1/8 tank.
Since I track my mileage, I could easily look back at similar tank fills, and see the corresponding distance. Typical 'damn, thats scary' happens at about 450 miles. This works out to 17.6 gallons of fuel, rendering 25.5 MPG. Yeah, I have a tendency to 'get on it'... heh. I'm normally one of those 'get it up quick, and hold it 10 over' type guys.
This tank, I did finally have to stop, as it hit the bad side of E about 10 miles from home, and all said and done, 514.2 miles on this tank! Pump said 17.7 gallons. 29 MPG!
Even after the fill, I continued the 'economic' style, and I have a very long trip ahead of me tomorrow, which I will continue to use it then as well. Don't think it will run me out of gas, but I'll have a good idea just by gazing at the needle to figure out about where it stands.