How do they do that?
OK, here is a good one for the list to chew on...
I have a 09 Nissan Murano. It has a lot of computerized information in its
displays. The two of interest for this challenge are "Distance to Empty" and
"Average MPG".
I have always used 87 octane fuel. I was on a long trip recently and I
stopped at a gas station that had a good price. I was disappointed when I
got to the pump and found that they had 10% ethanol in all three grades. I
have always tried to avoid fuel with ethanol added because ethanol has less
BTUs and I figure it would reduce my mileage. Since I didn't feel like
wasting my time to drive to another station, I decided to buy the mid-grade
since it was still less than what I was accustomed to paying for 87. I
figured the mid-grade might offset the ethanol mileage loss.
When I got back in the car the first thing that I noticed was that my "DTE"
was 428 miles..on 87 it is typically less than 410. This was the first thing
to surprise me..how did it sense that I put in a different octane fuel and
make an adjustment to the "DTE"?
So, when I got back on the expressway. I reset my MPG display. (I typically
get about 21.9 MPG at expressway speeds, 75-79) I drove nearly 400 miles
before refueling. My MPG was 23.5. At this stop I decided to push the
envelope further. I purchased the premium, 93 octane. This time when I
turned on the engine the DTE showed 468! Again, how is it able to
immediately sense what fuel I put in? After this, I drove for 331 miles and
averaged 25.8 MPG. I must say I was surprised at my results. I haven't yet
taken the time to do a cost / benefit analysis to determine the cost break
points. On a Honda I owned some time ago I did determine that if the
mid-grade was no more than 6 cents more it paid me to use it. However, using
Premium was not cost effective.
I just did a quick cost / benefit. In my area, mid-grade is 5 cents higher
than Regular and Premium is 7 cents higher than mid-grade. Based on that,
for 500 miles mid grade would save me $3.19 over Regular and Premium would
save me $7.15 over regular. Guess I might have to change to Premium..I think
I'll do a check on mostly city miles and see if it holds up.
So listers, how does the car's computer system immediately recognize that I
have just dumped in a load of higher octane gas?
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