The Finch Formerly Known As Gold

1 July 2006

Just a sip or two

Your friendly neighborhood governmental types say you should never, ever top off your tank, and for the last few years, I have evolved something of a routine: I stop when the pump clicks off, then squeeze in enough to round the price up to the next five cents. Assuming the pumps are calibrated to stop at more or less the same place, and given the fact that a nickel won't buy much gas, I can generally assume that I've reached an acceptable degree of tankfulness, if that's a word, and my gas-mileage computations will benefit, if not from guaranteed accuracy, at least a diminished degree of inaccuracy.

I bought Gwendolyn her first tankful on Day One, observing this protocol, and subsequently watched the gauge with some concern:

I wouldn't call her a two-fisted drinker, exactly: maybe 1.3, 1.4 fists. Of course, this could just be due to some quirk in Japanese fuel-gauge mechanisms that causes them to plummet during the first half of their range and then slow down a bit as the bottom approaches.

Which was a guess, nothing more. However, I filled up last night as the gauge grazed the one-quarter mark. (The 91-octane stuff she prefers was still under three bucks, albeit by a mere tenth of a cent.)

The owner's manual claims a fuel-tank capacity of 18½ gallons or 70 liters; the online service manual at Alldata says, again, 70 liters. The conversion factor is exact enough. The precious fuelstuffs flowed in, dollar by dollar, and then: click. I stared in disbelief at the pump. This can't possibly be correct, I thought: still, the click was indisputable. I went up five cents, then ten, finally fifteen, and quit.

Apparently at the one-quarter mark, Gwendolyn had used just under 10.6 of her allotted 18.5 gallons, 57 percent rather than the expected 75, suggesting that her gas gauge is even more alarmist than I ever imagined. I started her up, and the needle climbed to pretty much where it had last time, a needle's width above the F.

And those 10.6 gallons propelled her 263.7 miles, which means that through my usual around-town driving cycle, she averaged 24.9 miles per gallon.

I don't believe it either. Late June, A/C running more or less non-stop, the odd burst of speed, and still: twenty-four point nine.

Factoring out the World Tours, Sandy's average was twenty-three point nine — and she weighed 350 lb less and had something like three-fifths the horsepower.

Okay, smaller engine works that much harder. I understand that. Still, I have to admit that when I pulled into the station, I was thinking "If I can just get 19, I'll be happy."

And I'm thinking next time I might wait until the scary orange low-fuel light comes on.

(EPA numbers are here.)

Posted at 10:32 AM to Driver's Seat , Family Joules

I have the same problem with the Buick: 18 gallon gas tank, yet when I fill up with the needle in the red, a little over 12 gallons.

And I don't have the guts to ride around with a gas can in the trunk to test this theory out. Nope, rather spend more time at the station.

Posted by: Bill Peschel at 2:39 PM on 1 July 2006

It's a conspiracy, I tell you.

Sandy's Scary Orange Light went off in the middle of the Cross-Bronx Expressway during one of the World Tours. On a Sunday. I got all the way to Greenwich, Connecticut without incident.

Posted by: CGHill at 3:35 PM on 1 July 2006

You have an Infiniti G35, is that right Chaz? We have a Nissan Quest (same company, of course) and it has a screwy gas gauge as well. I.e., non-linear.

It's pretty annoying. So maybe Nissan/Infiniti is known for this. Nice vehicle though, and we may get another one now that the new models are out.

Posted by: Jeff Brokaw at 5:05 PM on 5 July 2006

It's an I30, a slightly older model (same platform as Nissan Maxima) with a smaller (3.0 liters) version of the same engine.

Although if this works out well, I'm up for another Infiniti when the time comes.

Posted by: CGHill at 5:38 PM on 5 July 2006

In the interests of experimentation, I went to yet another different station, and this time crammed the tank as full as I dared. The result: 19 and a fraction.

This tells me that I'm stopping too soon at my usual station, and that a more reasonable baseline mileage for this car is around 22 mpg.

On the upside, I paid six cents less per gallon than I did at last fill — and had I gone back to the previous station, I would have discovered that they've gone up another six cents.

Posted by: CGHill at 1:56 PM on 8 July 2006