Fuel Tank Capacity

I've always read that it can backfill into your Evap system and in some cars throw a CEL. Plus, you leave no room for gas expansion. Not worth the extra range.

EPA says not to top off

 

Going beyond the first click from the gas pump (filling up over the official stated fuel capacity of the tank) is only safe if you know you are going to burn that extra 2.1 gallons immediately after you do the fillup, i.e. if you are doing the fillup right before going on a greater than 120 mile road trip. The extra fuel is stored in the gasoline vapor pressure release valve and the overflow release. If the gas gets too hot and starts to expand there is a risk that the vapor pressure release valve or the fuel pump inside the gas tank could get damaged or its lifespan might be lessened.

IF that extra gasoline is not burnt right away AND it gets really hot and expands over the design limits of the tank THEN IF everything works the way it is suppose to THEN that extra gasoline that is now to hot to hold will escape through a tanks overflow/pressure release valve and your MPG will drop proportionally and your range for that tank of gasoline will not be extended.

A better and proven way to maximize the range of a Prius c is to drive under 50 mph and avoiding jack rabbit accelerations. Several people on Priuschat have reported being able to extend the range of a regular Prius hatchback over 700 miles per tank (usually getting +65mpg in the process) without overfilling their gasoline tanks -- just by driving the Prius more fuel efficiently. I am confident that once Prius c drivers learn more about their car - many of them will be able to beat the Prius hatchback with respect to range and fuel efficiency, too.

 

Way back before self-service, a gas pump jerk over-filled the tank on my little 4wd subaru wagon.
A few miles down the road we stopped at a store. (It was a hot day).

After a few minutes a guy ran into the store yelling for people to get their cars out of the parking lot.
I ran out and found gas dripping out of my car was running down-hill in the lot.
The little river of gas ran under about a dozen other cars.
Not only did he over-fill, he left the gas cap loose..
The car was parked at a slightly nose-up angle, which made the expansion worse.

Oh yeah, now I remember. He also chipped the paint (twice) near the gas cap cover.

Makes me really like self service..

 

In my Gen II, the model with the fuel tank bladder, the instructions were to fill the tank with the dispenser nozzle at the lowest flow rate, iow's, at the first click. I might do this on my C for the heck of it. Since it has no bladder to expand though, I'll probably be wasting my time now that I think about it.

 

Same in New Jersey, where you get full service and cheap gas.

 

^Having been raised in Oregon, I've never properly learned how to pump gas. Even though I'm certain it's the easiest thing ever, it makes me nervous on the rare occasion I leave the state

 

My sister-in-law never learned. She doesn't like the smell of gas..
Funny thing is, she had to learn to deal with the results of bad service.
Her 2001 Toyota Echo is very sensitive to over-filling and loose gas caps.

Every year I would reset her errors codes (& tighten the cap) so she could get her car inspected.
All she had to do was drive it for a few days and avoid gas station stops.

After a few years, I got her trained to tighten the cap and ordered her a code reader,
so she can clear out emissions errors as they occur.. (She has the list).
She leaves it plugged in, like it was a Scangauge2..

 

Alfon,

That would mirror, roughly, what others have seen here that overfill their tanks to the neck (at least in the liftback).

Realize, not everyone overfills to get the big range boost. Some do it to keep their fill ups "consistent" in a single tank.

My previous method was to fill on the slow setting and when I was within 2 gallons of the estimated shut-off value, I'd hand pump as slow as I could (so the vapor pressure wouldn't vary so much). After the first click, I'd wait 15 seconds and fill to the second click (usually 0.2 to 0.3 gallons) and end the fill up there.

I gave up doing that and just fill to the first click. My tank to tank variation hasn't changed significantly and I do calculate over the lifetime of my ownership (nearly 50,000 miles and counting).

 

I grew up in MN and have lived in Oregon since 2004. Once i was visiting MN and driving my brothers pickup, and had to fill it up. For what ever reason, I was just an idiot. Managed to spill gas everywhere...

Also I was traveling in Toronto once, and it took me for ever to get the pump started. Just couldn't get the damn thing to pump. And I had to get help from the attendant. Felt like a real #winner!!! DOH! Oregon really needs to drop this law.

 

Filled my tank on 6.11.12 after 545 miles -- 9.69 gallons, with a second click.

 

It creates good low-wage jobs for people who really need them, and doesn't markedly raise the price of gas for the consumer vs. the prices at neighboring states (due to slightly lower gas taxes). Oregon will never do away with this, just like they'll never approve a sales tax.