bigjacksauto

For those of you that are mixing E85 octane booster etc.
I am curious if anyone has ever checked exactly what is actually in the car gallons wise when the tank is on 1/4 or 1/2 or 3/4.
I believe the HHR ss is listed at 16.2 gallons capacity.
so in theory with some basic math

1/4 tank would be 4.05

1/2 tank would be 8.1

3/4 tank would be 12.15 gallons

full tank would be 16.2 gallons

But as we all know most of these cars will hit the full mark well before they are actually full.Another words maybe the full mark is actually showing us that we have 15 gallons of gas and then of course that would throw the rest of the measurements off
half would be 7.5 gallons etc.

I know strange ? but I like to be exact when mixing anything.

With my torque app it does show a reading from the computer of about 41% full when the car is 1/2 full on the analog gauge of course not sure which I can trust.

donbrew

My experience is that the gauge is very accurate. Meaning 1/2 = 8 gal.

It only looks like an analog gauge, it is really digital. That's how the miles to go and MPG is so accurate, even if you don't fill the tank all of the way.

When I fill up (every day) the auto cutoff only leaves about a quart or 2 until over flow.

badassbowtie

I have run my tank way down and filled up with about 15.5 gallons...I assume when it clicks off, your at 16.2...Filling up when the "LOW FUEL" warning hits is about 15 gallons...I think you should just fill it up with 7.5 gallons of E85, and 7.5 gallons of 93...for 15 gallons, then you will know its spot on...Although you wont be completely full...

Oh and one other note...Im sure you know this, but if you park unlevel, the gauge wont be accurate for a few minutes down the road

07azhhr

I have taken my car down to almost complete empty before ,not the norm though even though it happened again today, and thus have seen a tiny bit above 16 gal's before. Being that I am at that point right now, I will have to leave early for work to fill up on the way since I forgot to do so on my way home yesterday. My miles to empty showed 17 miles when I parked it this morning. I will report back with how much I can get in there.

FWIW the tank is 16.2 but the filler neck will allow for a tad bit more fuel to be pumped in.

Radco

IMO for the tiny bit of difference I would not sweat it being perfect mix.. alittle off should not hurt anything.. I am a tad anal in things being spot on but I wouldn't lose any sleep on this one :)

donbrew

The last time I ran it dry, I poured a bit less than a gallon from a can in then drove the 200 yards to the gas station and pumped 14.9 in on the 2011. Back on the 2008 I once pumped 15.95 in, I think the "flex fuel" bits take up some space in the tank.

bigjacksauto

All great points.
So when its saying 1/2 everyone agrees so far its actually 8 gallons?
Guess the only true way to tell is if someone ends up running out if gas then adds 8 gallons and sees where the gauge is at.

843de

Some interesting thoughts and observations, but don't "run 'em dry", the fuel pumps are submerged and liquid cooled by the fuel. A few percentage points either way isn't worth the expense of replacing a fuel pump, and gas gauges are calibrated to give you the approximate fuel level, they aren't precision instruments by any means.

SS fan

You all must like walking more than me. I got the lowest I have ever run one today, filled it up and it took 13.5.......

07azhhr

When I filled up today I was below the empty line. It only took in 14.6 gallons. When full it put the needle beyond the full line on the gauge. So it looks like I truely still had just under 2 gallons of fuel in the tank. This seems to suggest the gauge is setup to show empty but give you a small reserve. The 17 miles to empty I mentioned earlier should have been around 3/4 gallon of fuel. I only drove about 1/2 mile to the fill station so probably a 1 gallon reserve.