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candf
04-06-2012, 09:42 AM
I have found the MPH average reading on the computer pretty accurate but not the estimated number of miles left that it is reading. The computer said I had 52 miles left to drive when I filled up and I put 10.84 gal in so at the 28.72 mph I got with that fill up and 4 gallons left, I should have had 114 miles left to drive reading on it. This is the first time I had a car with a computer like this. It that pretty normal to be over half off on the estimate on these computers?

inodes
04-06-2012, 09:49 AM
I have found the MPH average reading on the computer pretty accurate but not the estimated number of miles left that it is reading. The computer said I had 52 miles left to drive when I filled up and I put 10.84 gal in so at the 28.72 mph I got with that fill up and 4 gallons left, I should have had 114 miles left to drive reading on it. This is the first time I had a car with a computer like this. It that pretty normal to be over half off on the estimate on these computers?

Good idea Candf. I'll do the same thing when I get my car back tomorrow.
I'll post results.

hooked
04-06-2012, 10:57 AM
I suspect that the number of miles left value is very conservative because Mazda wouldn't want a ton of complaints from drivers that were stranded when their vehicles ran out of gas even though the computer told them they still had enough. Keep in mind that these numbers are all estimates, because you could be stuck in horrendous traffic on that last 1/8 of a tank and your miles-to-go value would drop from 114 to 60.

In my other vehicle that had a trip computer, the display would show "Low" as the gas gauge hit the "E" so you wouldn't try to squeeze as many miles out of the tank based on the computer calculations before pulling into a gas station.

candf
04-06-2012, 12:34 PM
[QUOTE=hooked;5925437]I suspect that the number of miles left value is very conservative because Mazda wouldn't want a ton of complaints from drivers that were stranded when their vehicles ran out of gas even though the computer told them they still had enough.


Makes sense. Thanks.

VK Sefirosu
04-06-2012, 01:08 PM
On my Mazda3, there was definitely a security gap when the fuel light lit up. If I remember correctly, the fuel tank was supposed to contain 55L and usually when I fueled up at that time it was ~45L to full.

That is not scientific at all and I'd really like to know the real gap they use (haven't been able to find it in the manual) but it is probably the same in the CX-5.

Modshack
04-06-2012, 04:35 PM
A lot of Car computers will show Zero miles to empty, even when they have anywhere from 1-2 gallons in the tank...

Pretty normal stuff (to avoid you getting stranded)

prhac
04-06-2012, 05:38 PM
A lot of Car computers will show Zero miles to empty, even when they have anywhere from 1-2 gallons in the tank...

Pretty normal stuff (to avoid you getting stranded)

Yep. Fairly typical - some manufacturers used to say there was about a gallon left when empty showed.

inodes
04-06-2012, 09:41 PM
In the user manual it highlights the need for the diesel to never get to less than 10L in the tank. I wonder if there is a reserve tank in the diesel.
The petrol doesn't get such recommendations.

GAXIBM
04-06-2012, 09:53 PM
Candf - you probably did not get it completely full so subracting the fill from the capacity may not yeild what's in the tank - overfilling can be hard on the tank vapor capture & recovery system. Also most fuel injected cars have a fuel pump in the tank that depends on having liquid to keep it cool, if you do run out of gas you could damage it...