Gen Ii Brimming The Tank...

[defender]

I've just got a 2008 prius and I'm loving it. Went to fuel up for the first time today though and it seemed to take a hell of a lot of fuel after the fillers automatic stop. I kept putting more and more in and eventually gave up as I was worried it might be going somewhere else and there was a queue behind me... I've never really brimmed any car but thought I'd start taking the MPG thing seriously, so I'm just not used to it! Is this normal?

[wizzlon]

I've just got a 2008 prius and I'm loving it. Went to fuel up for the first time today though and it seemed to take a hell of a lot of fuel after the fillers automatic stop. I kept putting more and more in and eventually gave up as I was worried it might be going somewhere else and there was a queue behind me... I've never really brimmed any car but thought I'd start taking the MPG thing seriously, so I'm just not used to it! Is this normal?

I find that it does take what seems a lot more once you think the tank is brimmed. I have to pull the nozzle back to stop the auto cut off and gently feed it until it is properly brimmed. It can spit back a bit so be careful.

[timberwolf]

I am not sure that brimming the tank is a good idea, the Prius contains a charcoal filter as part of the closed system.

[Dave R.]

I've just got a 2008 prius and I'm loving it. Went to fuel up for the first time today though and it seemed to take a hell of a lot of fuel after the fillers automatic stop. I kept putting more and more in and eventually gave up as I was worried it might be going somewhere else and there was a queue behind me... I've never really brimmed any car but thought I'd start taking the MPG thing seriously, so I'm just not used to it! Is this normal?

If you are filling the tank (e.g. till the automatic cut-out and then a drop), then, provided you look at data over a number of fill-ups, the error caused by not quite filling to the brim will be quite small.... if you think about it, if you look at data over, say, 10 tanks full, then the error in mpg is down to (worst case) 5 litres over 350 litres, i.e. 1.4%

If you are serious about tracking your consumption, try www.fuelly.com to maintain a record (though make sure you set your units to UK Gallons!)

[johalareewi]

isn't it a bit dodgy to fill to the brim? Fuel from the forecourt tanks is fairly cool and once in your tank, will start to warm up and expand (in the summer!!). If you have brimmed the tank, there isn't much room to expand into.

I am also finding that as the tank empties, the mpg gets better. I guess because there is less weight in the fuel tank to lug about?

[Jan&tone]

isn't it a bit dodgy to fill to the brim? Fuel from the forecourt tanks is fairly cool and once in your tank, will start to warm up and expand (in the summer!!). If you have brimmed the tank, there isn't much room to expand into.

I am also finding that as the tank empties, the mpg gets better. I guess because there is less weight in the fuel tank to lug about?

I remember reading somewhere that when they do these supervised fuel road fuel tests, the tank is emptied and then a measured amount is put in, usually one or two gallons - hence unrealistic results - whoever just puts one or two gallons in.... frankly i'd rather have a full tank before I start a journey - invariably there and back plus some and then fill up at one of two or three pumps in tesco's... On my Prius i've been averaging 58 to 60 mpg over the last two years (it's 2 years old tomorrow) and the wife's Aygo has done 260 miles local running around since the last fill up

Basically I'm over the moon with both cars - the amount of tax I'm giving to the Government in fuel and road fund licence now compared with my old Avensis tspirit and the wife's old suzuki alto automatic is minimal and I'm happy

[timberwolf]

Anyway, putting in less than 4 gallons confuses the Prius computers on a Gen 2.

[johalareewi]

I'm sorry Dave, I can't let you do that....

[defender]

Thanks for the info. I'll just fill it till the pump stops from now on.. Have signed up at fuelly, will try to keep it updated!

[Chris Dance]

I always fill the tank of my Prius to the very top if I am doing a long journey. I did read somewhere that "brimming" the tank is not good because there is a bladder in the tank which could be damaged? Has anybody else heard about a tank bladder?

[fuel miser]

I always fill the tank of my Prius to the very top if I am doing a long journey. I did read somewhere that "brimming" the tank is not good because there is a bladder in the tank which could be damaged? Has anybody else heard about a tank bladder?

Yes, but only on the US gen 2 Prius in order to comply with strict Californian 'vapour leakage' legislation.