Automatic Transmission "best speed" test...

[GasSavers_Chico]

Well, been lurking and adding gaslog entries for a while now, and finally have something that is possibly worth posting... possibly. Wife had a late work night, so took the opportunity to do a little "optimum speed" testing. I've theorized about it (at least, for my car), but finally had a moment to test it out. I drive a 2002 Ford ZX2 with the 4-speed automatic (I think it is a kind of CVT-ish thing, but the shifter shows 4 speeds. I have a small air dam, Amsoil 0-20w and a K&N filter. Anyway, here you go:

I've wanted to know what the best speed was for this car, mileage-wise. To that end, I went up and down a 1.5 mile stretch of road near my home, resetting the Scanguage trip MPG after I got up to the testing speed. The road is two-lane with some straights and some curves, with a fair amount of ups and downs. I'm not sure what the overall elevation change is, but one end of the test section is higher than the other, making "uphill" and a "downhill" runs. I used cruise control for the testing.

OK, on to the results...

Remember, 1.5 miles, uphill and downhill...

55 MPH Up = 36.2 MPG
55 MPH Dn = 39.0 MPG
Avg. = 37.6 MPG

50 MPH Up = 38.8 MPG
50 MPH Dn = 42.1 MPG
Avg. = 40.45 MPG

45 MPH Up = 41.6 MPG
45 MPH Dn = 46.2 MPG
Avg. = 43.9 MPG

40 MPH Up = 38.7 MPG
40 MPH Dn = 41.1 MPG
Avg. = 39.9 MPG

I've always speculated that somewhere around 43-45 MPH was the best speed for this automatic car. I think that at 40 MPH, the torque converter wasn't fully locking up (that's a guess). If I had attempted 35 MPH, I'm prettty sure the transmission would have bounced between 3rd and 4th. Plus, I probably would have been run over.

Anyway, I'm happy to have finally tested this out, even on this short section of road. I'm wondering if other owners of automatic cars are experiencing the same things. I won't double post it, but maybe this should go in the automatic section...

I love coming to the site and seeing what the latest information is. What a great place to learn and exchange ideas on what is a very important topic!

-John