Kizashi Club

There's something kind of weird going on with my AVG MPG display today.
I filled up on Friday but then didn't drive it this weekend. (had the grandkids and we haul them around in the van usually) I drove home from the station which is about a mile in a 45 MPH zone. So when I get home, the AVG MPG is usually about 15. Normal and then it starts to go up as I drive on the interstate on my way to work. Well, on my drive on the interstate this morning, I glanced down and it was about 35. HUH??? As I kept driving, it kept climbing. All the way to 37 before I exited and then went down the side roads. By the time I got to work, it had dropped a few tenths due to stops and acceleration, but it's still 36+. I know driving from driving the interstate for some distance will put me in the low 30s, but this I've never seen before. Is it the gas? Doubt it. Did my engine suddenly become much more fuel efficient? Doubt that too. A few weeks ago, I filled up on my home from a weekend trip about 120 miles from home. When I arrived home, the gas gauge was still just a hair above full. After 120 miles. It had come down from the initial full level, but after 120 miles, I should have been down to about 3/4. Unfortunately, I didn't calculate the mileage on that tank but I think I went about 400 miles on the tank. So I wonder what's going on here.

The only explanation I have for this is that you must have inadvertently reset the Average MPG display. Therefore, once you got gas, it was averaging only from the miles you drove since fill-up and did not have the low figures from before driving down the new average.

You are also certain you are not talking about average MPH vs. MPG, right?

KuroNekko wrote:

You are also certain you are not talking about average MPH vs. MPG, right?

That was my first thought....

Ronzuki wrote:

KuroNekko wrote:

You are also certain you are not talking about average MPH vs. MPG, right?

That was my first thought....

Well that would be a possiblity if the AVG MPH had tenths, but it doesn't. BTW - I do reset the AVG MPG when I fill, but since I do it all the time, I know what's normal and what's not. Since I do stop and go at the begining of each tank, it's starts out low and climbs. However, it's never climbed into the 30s before. Much less 35.

So on my way home today I had to drive for a few miles on side streets. 35 mph or less. The AVG MPG dropped as expected, down to 34.5. Once back on the interstate, it started climbing again. Up to 35.5 before I got off. This is weird. Also, the DTE was over 400.

Could your starter battery be dieing? That could cause intermittent resetting of the trip computer when you start the engine.

I'd kill for that kinda efficiency!

I wonder if the fuel sensor is kaput?

I think his point is that even with reseting intentionally or not, he's never seen figures that high.

Maybe the gas station n put V-power in ur tank. Didn't someone say that gives higher mpg. Or maybe you got rid of a lot of weight on your car.

The 120 miles on highway without the needle dropping much is normal. And deceptive. My first half of the tank seems to disappear much slower than later half, per dash instrumentation

I get out of the original post:
- vehicle filled on a Friday and then parked in garage for 2 to 3 days
- start vehicle on Monday(?) and head straight onto "interstate" (so a freeway), then notice average is 35mpg
- average keeps increasing until heavier traffic encountered, then reduces

It fits with the starter battery being on the way out. You will lose the trip computer average consumption when the vehicle's engine is started and your battery is on it's "last legs". The vehicle sat for a couple of days (so the battery had time to drain/ self discharge) before the next start. The first time the average consumption is noticed is on the interstate- so the trip computer could have reset at that morning's start, but wasn't noticed until after the short drive onto the interstate. (37mpg is 6.4l/100km and could easily be obtained as an average if the computer was reset just prior to entering the interstate.)

During my trip to Florida couple weeks ago mine hover around 37 and 38 few time but on my return trip it stayed at 27 or 28.