Coming back from Reno today in my Swift, I took the old highway so I could go slower than the freeway. Another part of the reason is because there's a certain hill on that route I thought would be good to do some hill climbing testing. It's one of those hills where you may make it in top gear or not depending on which way the wind is blowing & whether you have the weight of a full tank of gas or not.
First I tried it at 55 mph in 5th. It wouldn't *quite* maintain 55, but did close.
Then I tried it at 50 in 5th. Same deal - the speed lagged, but I kept it floored.
After that, I did it in 4th at more speeds. Results follow:
5th - 55 - - 25.6 mpg
5th - 50 - - 25.7 mpg
4th - 50 - - 24.7 mpg
4th - 45 - - 26.0 mpg
4th - 40 - - 26.9 mpg
4th - 35 - - 27.4 mpg
During the research I was doing in conjunction with my engine replacement project, I came across the engine's performance specs that max torque was at 3000 rpm. So the next thing I did was to see what speed 3000 rpms came to in each gear. Results follow:
2nd gear - 3000 rpm is 27 mph
3rd gear - 3000 rpm is 40-41 mph
4th gear - 3000 rpm is 56 mph
I didn't check it for 5th this time, but seem to remember it's like 65-70 mph
So it seems my best mileage (so far) going up that hill is 4th gear and well below the torque peak. Since I was on "current" trip mode, I wasn't looking at the throttle position, but I wish I had been, now.
But if I'm ever heading up a mountain on a freeway and can't hold 5th, at least now I know that trying to hold 56 in 4th should be at it's torque peak.