It does help cool it but I've never understood how that fact can extend to running it low can really increase the temperature all that much. I googled and lots of people talking about this but I saw nothing that concludes with real evidence one way or the other!
Most vehicles these days have electric fuel pumps located in the gas tank. By keeping the tank over half full the fuel pump electric motor is cooled by the gasoline. Also i don't want to suck the gunk at the bottom of the fuel tank into the filter or injectors.Maybe i'm lucky but last 6 vehicles our family had all went over 100,000 miles and never replaced a fuel pump or starter (synthetic oil )easy starting in winter. The chevy actually had 160,000 miles when replaced.
The 1/4 tank advice as far as I know is more for emergencies (esp. in the winter) in case you get stuck and you have to idle the car (again in the winter to keep warm). It also depends how big the fuel pump is. I mean, when the low fuel light comes on at 2.x gallons, that's still quite a bit of fuel (just imagine two milk jugs laid down on their side). I don't believe the gas tank is much bigger than two laptops side-by-side in terms of length and width.
Some (I'm pretty sure nearly all) in tank automotive fuel pumps are cooled directly by the fuel being pumped through them, motor and all.
According to the owner's manual, when the last fuel marker starts flashing, you have approximately 1.6 gallons of fuel remaining. I average 45 mpg, up and down mountains, freeway and city combined. To be safe, I figure 60 miles.
It's a little more than that. Toyota usually gives 10 litres (2.6 US Gal) as a reserve and it's been fairly consistent for me.
I can confirm that. On 3 Toyotas (Yaris 2003 petrol, Auris 2008 petrol, Auris 2010 diesel) - when the lowest bar starts blinking engaging low fuel warning there is at least 10 liters in the tank. Last week I've been driving from Italy to Poland with mid-fuel stop near Innsbruck Austria (ON there was @1.3 EUR/ltr compared to 1.5 EUR/@ltr in Italy and Germany). On my way I've managed to get 900 km on 44 litres of ON while driving at 110 / 130 kmh (Auris Diesel). So in this car 10 liters on this situation would be enough for 200 km. In winter, with city driving it would last for about 100 km, so I think that it is OK with DTE switching to 0 with Low Fuel warning, rather than empty tank (Especially in diesel which is much harder to start after emptying tank). I allways refill at two bars, and for all Toyotas refills varied by about 0.5 liter depending on driving style, fuel station and so on. Assuming Prius consumpion at 5.0 l/100km it gives 700 km range, with about 100 - 150 km of safe "emergency range" (in case you miss fuel station on highway - sometimes next one is 70 km or more) and 50 km of "It will make or it will not make it" range. Quite OK for me. Max fuel I've managed to put to the car was first Auris. In PL when you take car from a car dealer (at least Toyota) you get fuel only to reach the nearest fuel station (if the dealer would buy a fuel for you hi is encouraged to pay 23% TAX, and then he had to add another 23% to you - they don't have special license to sell fuel). Until first stop it filled with 52.3 litres of gas (while having 55 litres fuel tank). Later I never reached 46 liters border. S.
I reset my B trip odometer when the last bar starts flashing, as that is what Bob Wilson reported on with his "run it out of gas" tests. He reported approximately 2.1 gallons left when the last bar starts flashing. I have 3 tanks over 700 miles and two of those I ran about 95 miles after the last bar started flashing.
On my 2010 Toyota Prius III, its been fairly consistent. When the last pip on the fuel tank level has JUST started blinking then I can fill up with alittle over 9 gallons of gas. When the trip odeometer has JUST started displaying 0(zero) Miles to Empty then I can fill up with alittle over 10 gallons of gas. I've never driven more than 37 miles past the distance/time when the Miles to Empty display reached zero but I've never used more than 11 gallon. I drove pass "0 miles to empty" twice this summer (1st time @68 mpg, 2nd time @70 mpg <= via hypermiling). However, the Prius mileage will drop in the fall and winter time so to be on the safe side when the temperature drops below 40F(in the winter and fall) - right after the "0 miles to empty" is displayed, A non-hypermiling driver should have the about 1.8 gallons left in the tank which should give about a 75 miles (@42mpg in winter time normal driving) to 36 miles (@20 mpg if you get stuck for one hour in an urban traffic jam a snow blizzard ) range before the last drop of gas out of the tank - which is a very bad thing. FWIW - I've read that one can wiggle the Prius slightly after the initial top off and get slightly more than 12 gallons into the tank ( some say this extra gas gets stored in the gasoline tank's vapor/pressure valve which is not a good long term storage location but others say that for immediate usage and short term storage to extend the range of a very long trip that this is a useful technique to extend the Prius' range). hope this helps Walter Lee 2010 Toyota Prius III, BlueRibbon/Dk Grey, oem floormats Yokohama Avid S33 (50/48) ScanguageII, 100% grill blocking Odeometer 15800 miles/overall 60 mpg Best tank 9/29/2011, 727 miles/10.25gallons of E10, 70.9mpg MD/DC/VA metro area
I have a 2011 Prius My last fill up the read out was MTE zero and I drove 34.3 more miles while on zero before I filled up. I filled 10.244 gallons of gas. I get only around 46-48 mpg since I am an aggressive driver.
I have filled to the top of the neck a few times now and I can get in about 2 extra gallons of gas. The real tank capacity is probably about 13.5 gallons. The benefit is an additional 100 miles or more on the tank. Nothing in the owners manual that I have states you can not fill the tank up to the neck, if there is please let me know.... alfon