Here is a strange one for you. About a week ago I unloaded the NAV DVD and turned off the MFD. I still get the volume control and Bluetooth prompts at the top of the screen, and hopefully other more important prompts if they occur. I don't ever use navigation, and seeing it tick away over there all the time seems like a waste. I drove back and forth to work like usual last week and noticed a significant change in vehicle-reported miles-per-gallon. I don't ever bother with a manual calculation since the number I see seems reasonable. I usually drive the same route everyday, 140 mile round trip, 5 days a week. My roundtrip average is usually in the 50-52 mpg range. By mid-week my mpg was better than 53, and by Friday it was 54.6 mpg. These higher than normal values continued into the weekend running around town. Nothing else has changed with the vehicle, no recent maintenance or tire changes. Even the weather is the same, a rather warm February thus far. I will continue to monitor and maybe do some manual calculations to confirm. I don't think there is any connection between NAV and MPG, unless I'm missing something. Thoughts?
There is very little difference in actual fuel used between 52 and 54 mpg. It makes me wonder if it could be attributed to something like seeing the navigation bothered you and made you accelerate differently because of being annoyed. My own Prius can sometimes fluctuate up to 5 mpg on the same route day to day. Usually it's weather but every once in a while there doesn't seem to be a reason for it. Interestingly enough my scangauge has indicated when it's a "bad" mileage day it seems to start out worse from the beginning of the drive. 12v battery charge level maybe. There are probably a lot of factors I don't even consider. You will probably only be able to tell by tracking it long term.
It might be useful to measure the electrical load with and without the Nav enabled. Use MiniVCI or equivalent to monitor the traction battery current with the engine off. The cycle the nave unit ON and OFF. See if there is an appreciable change in current draw from the traction battery. Bob Wilson
So Monday and Tuesday I was driving in 40 mph headwinds and the mpg dropped back down into the 48-50 mpg range. Yeah, probably just a placebo effect of some sort. I'll keep an eye on it. Usually an mpg thread is about the numbers going in the other direction and the "how come".
Still monitoring the situation, and with lighter wind speeds now the mpg has increased back up into the 53-54 mpg range. I have confirmed the reading with manual calculations on the past 5 refills and it is within a couple tenths of a mpg. Everybody is waiting for the other shoe to drop when I put the NAV disk back into service. Stay tuned.
I drive same route every day for work. I drive south in morning and north at night. When I have 5 to 10 mph wind, it lowers my mpg by a few mpg. Or it is more then I only get about 35 mpg. I normally only get 39-40 in winter and 42-43 in summer. I live in southern Oklahoma and it is always windy. Worse in the summer. When car was new, I bought 100% gas but now the SAMs club only has gas with 10% ethonal. In summer I was getting 43-45 mpg and then after recall update it stays closer to 40-41 in summer. That is on my daily drive of 37 miles each way. N long trips, it gets better about 44.
