Fuel Tank Size

( Many North American Gen 2 owners ran out of gas, as the fuel system made it hard to guess how much gas remained. As a result, Toyota is very conservative with all current models)

There is a considerable safety margin when your Prius c says you have 0 miles left. It is very bad (compared to most cars) to run out of gas in a Prius, so unless you have plans to carry 3 or more gallons in a can with you, it is not sensible to exceed 0 miles by very many. (Not all Prius owners are sensible)

 

How are you extrapolating to a 7.5-8 gallon tank, when you have never run it dry nor down to that level?

As Jimbo indicated, the gauge and range calculator set aside a considerable safety margin. This practice is normal throughout the auto industry. The gauge components are cheap and inaccurate and variable from car to car. And fuel consumption is very highly variable due to many factors that most drivers never think about, but the car cannot predict on the route ahead.

If the range calculator had no safety margin, that short-term MPG variability would cause drivers to find their cars prematurely running out of fuel nearly half the time. This would prompt many angry calls to Customer Support, causing considerable grief for the workers there. The best way out of this is to build in enough margin that even the 'normal' inattentive drivers have so much warning that when they finally do run out, which many will, they cannot reasonably shift the blame to anyone else.

For an example of the typical margin in a Gen3 Liftback, read the base posting of [WARNING] Running out of gas (Gen III). Bob does these sorts of tests for fun and sport and engineering curiosity. Your 'c' has a different margin, but I don't recall anyone testing it to similar precision.

 

I believe conventional wisdom for the c is that when your range equals zero, you have 1.5 gallons of gas left. There is at least on other thread where drivers discuss how far they've gone with zero bars on their gas gauge.

 

At least being the key phrase... a simple search would have answered this one easily a number of times.

 

Despite the fact the tank is rated at 9.5 gallons.. I've seen fill ups that exceed that amount.

though having the tank that empty is pretty damn risky.

I never pay attention to the range calculator thing. once the car beeps and the gas gauge starts to flash at you.. you're looking at filling at least 8 gallons. (in other words... about 1.5 gallons of fuel left)

Nexus 7 ?

 

The tank is rated at 9.5 gallons / 36 L in all markets.
The last 4 times I have filled at the warning light the tank has taken between 8.4-8.7 gallons. I always fill asap after the light comes on, at the same pump to first shutoff.
This is significantly less than the forum suggestion of about 1.5 gallons left.
Ignore the range calculation, and get to a gas station asap after the light comes on.

GT-I9300 ?

 

When the gas tank is designed, the float that measures the level often is positioned so that the level indication that represents the so-called 'low level' warning light is often represents 3 gallons left. Car owners have gotten so inept at caring for vehicles that a reserve of a hundred fifty miles or tire pressure monitors are necessary. If your fuel runs out and the injectors not lubricated by fuel or the tire pressure gets too low catastrophic things will occur and the lawyers keep making money on such. The fuel left is not an indication of the tank capacity.
Specs (bet you didn't read that either) say the tank capacity is 9.8 gallons (37 L) but knowing manufacturers its likely 10 gallons (40L). Watching your mpg readout after resetting at refill you can stretch that mileae per tank to more than 500 miles. However, running the tank as nrar empty as possible has no benefit so refill at any time down to the warning light is better practice..

 

Wise words.

When my "range" gets down under 10 the beep and flash can come on at any time.

Sometimes it starts beeping & flashing and range goes to "0" immediately - even when the range is showing 8 or 9.
YMMV

 

Coming from my 2001, although I'm getting much better mileage on the C, I find I'm running the tank nearly empty more often on the C- the 2001 bing'ed at you at every startup when the fuel got low, but the C's fuel low indication is very soft and subtle and I keep missing it- I think I've seen it pop up only once since I've owned the car.. I think the other reason is a user-interface design thing: in the 2001, the fuel level indicator being up in the top display and separated from the info screen meant I actually noticed the fuel level, vs the C, where I find that I'm actually staring at whatever stats I've got up on the LCD display and I simply don't notice the fuel level getting low..

 

I ran mine pretty low on the last trip to see how far it would go (only had it a month) though I'd have preferred to have a gas can with me just in case. Anyway. doing 73 MPH or so on I-75 in the mountains of northern TN, I went another 35 miles from the time the gas light came on and 18 miles after the last segment on the gauge disappeared. The car calculated I had gotten about 45 MPG in that 35 miles. I put 9.54 gallons in the tank so I'd say I was nearly on fumes. I was expecting a bit more cushion actually. My calculated mileage for the whole tank was over 47 MPG (448 miles), which was pretty much all highway, while the car indicated over 49.

 

i have never gone beyond the blinking light

 

I wouldn't do that anymore; there's really no upside, and bad things can happen, in particular to the hybrid battery. Maybe the fuel pump too.

I would make it a rule to always refuel when it's down to a couple of bars remaining, minimum.

 

Do you have a Prius 'c', as suggested by this forum name, or still the Liftback as indicated in your profile?

 

Both. My wife drives the full-size while I just got the c.