Well my experiment started off fine until I got to the highway. The TPMS light came on again from a problem valve and the VSA turn on when that happens and wont turn off again until the light is off. I added the air in the tire while putting on my work boots.
I filled up after work at Shell and reset everything and drove home which I was further to the highway. I drove with both the VSA and ECON off. The temps out side was 14 degrees and usually have about a 8 degree difference in intake temps but the temps where 27 degrees at 60 mph. Timing was also 31/33 degrees. The fuel trims when about 2 percent leaner from normal. Short term and Long term fuel trims are in percentages so a 10 long term is 10 percent more fuel. With the lights and heat on there are too many variables but with the ECON off and VSA with a full tank my iMid now reads 43 mpg and a range is at 560 miles which is higher than I got all winter and that would be with my 60/40 highway. On a flat part of the highway at 60 mph I turned on the ECON at the timing went up to 36 but started to fall and the fuel trims went to 10.3 normally what I see. Then I threw on the VSA and about a mile the timing was 28 degrees from 31/33 so I think there is a learn curve and yes I would say there is more timing with the VSA off. I also noticed that both fuel trims at cruise both off were the same compared to 1 being higher. I cant wait for the drive to work tomorrow with no lights on but expecting snow so I might have to wait a few days.