mileage off on dash

Is Trip A or Trip B involved somehow?

 

the police dept. in my town has a little trailer w/mileage display so when you drive by it you can see how fast you're going, I drove by w/ my 2004 prius w/cruise set at 32 MPH, the display said I was going 30, this way toyota is helping me think I'm getting better mileage.

 

My MPH reading matches my GPS.

 

xerox, have you compared your dashboard display and Scan Gauge against a GPS measured distance? That might give you an idea if the Scan Gauge is giving an odometer reading or an intermediate value that is ultimately corrected for the display readout. Because your values differ by <3%, I would try for as long a GPS measured trip as possible.

For what little it is worth, my dashboard display matches my GPS readout (Garmin unit) and any radar trailers I have driven by. Personally, I put the least faith in the radar trailers. I don't have a Scan Gauge.


Tom

 

Interesting! All then GenIIs and GenIIIs read approx. 2mph too fast when compared to GPS (accuracy 15' or less) and radars. Even the Scangauge read accurate with GPS while speedo was 2mph too high. The c's must be dead on. That's a first for the Prius.

 

Actually, my GPS reading is coming from the built in NAV unit in my C. I assume the speedo and the NAV speed reading are two separate readings, but who can tell for sure?

 

Take it to the dealer and have them give you an explanation for the discrepancy. I think they should be the same and that's nearly a 3% error against your favor. This cheats you on your warranty and depreciation so be sure to let Toyota know you want a 3% refund of any money you paid them for compensation for the accelerated depreciation and any warranty work will go by the scan gauge reading.

 

Does a GPS-measured distance typically take elevation into account? If you spend a lot of time driving up and down gentle inclines, that could make a difference.

For example if you went on a trip where, the whole time, you are either driving up or down a 10-degree incline, then your odometer would show a distance 1.5% greater than what you'd measure from assuming it's all flat.

 

How are you reading the mileage, odometer, with a scan tool?

I read my mileage with a SGII on the Tank Trip on each refill. The SGII will show about 4-5 miles lower than the odometer between tank refills.

I sent LinearLogic an email asking how they calculate their miles and was told that it was proprietary ??!! They did tell me that most feedback they get is that the miles, mpg and mph are typically lower than the Prius display but that their mpg is closer to the actual mpg than the Prius display.

 

This maybe a stupid reply, but I'm wondering if it has to do with the electric motor system. Maybe the miles being read with the tool are reading combustion engine miles only, where the excess miles being read on the odometer calculate all miles including miles ran on both gas and electric. On side roads my car really doesn't use any gas so the engine doesn't kick on for a little bit.