On (Not) Running Out Of Petrol

[Rabbers]

Some recent Topics, e.g. "Tank Range" and "Fuel Warning Light" have skirted the

subjects of the tank running dry and driving on reserve. Out of pure curiosity, I thought

they might be worth a closer look.

Conventional wisdom, perhaps erring on the side of caution, tells us that running out of

fuel can (a) damage the fuel pump, and/or clog the injectors and fuel filter with gunge

dredged up from the bottom of the tank. And if we make a habit of driving on reserve,

the likelihood of one day needing to replace the parts in question is said to increase. We

are also told that low fuel can lead to stalling when a car is driven uphill, the only sure

way of totally eliminating the risk being never to drive with the tank less than a quarter

full.

Of course, drivers who enjoy seeing how far they can travel on reserve are not going to

forgo the delights of a clenched anal sphincter by following the dictates of caution, but

if they should ever run out of fuel on a motorway, they would be well advised not to

admit that they were conscious of the possibility, let alone that they were in the process

of testing it. In some countries, the initial offence of running out of fuel, usually punishable with a simple fine, might otherwise be compounded by a charge of reckless driving, which could lead to complications that do not bear thinking about, especially if an accident has occurred.

Which brings us to the specific, and largely hypothetical, question of running out of

petrol in a 300h. According to my dealer, who also sells Toyota, none of his customers

have ever reported doing so in a hybrid. This he attributes to drivers of hybrids being

"more prudent and rational in their thought processes than most people" (I'll take his

word for it), but also to the reserve settings in what are already very economic cars

being designed to give plenty of warning that you should get to a pump. The 300h

warns you at 13-15% capacity (which is a long way short of the aforementioned 25%

but good enough), meaning that you have, very pessimistically, at least 120km before

running dry. Which, of course, should at all costs be avoided, not only because hybrids

share all the potential empty-tank problems outlined above, but even more especially

because of the dire consequences of the main Battery becoming so depleted that it

will fail to fire up the petrol engine as it is programmed to do. After three attempts, it

will recognize there is no fuel supply and completely shut down pending refueling and

a resetting of the fault code in the engine computer, the latter operation being possible

only in a Lexus or Toyota workshop to which the car will have had to be towed (remem-

bering to keep the rear wheels off the ground if a flatbed was not available). What this

would mean in terms of cost and inconvenience I dread to think - and, frankly, I prefer

never to find out.

[steve2006]

At a slight tangent but fuel related I was travelling southbound on the M1 yesterday and noticed one of the portable matrix signs was illuminated with the message "12 cars have run out of fuel in June check yours"

Interestingly the sign was positioned around 800 yards before the services, probably sponsored by Esso who would be more than happy to take £1.50 a litre off worried motorists!

[Blisteringblue]

I'm getting braver, drove on for 30 miles after refuel was at Zero. Still barely registered 60 litres when filling. I still can't understand why they have to be so conservative but you are right you will have to be crazy to run it till you do run out.

[Steve44]

sitting reading the pdf copy of the owners manual, whiling away the days till delivery , noticed it states a minimum of 10L petrol is needed to put out the low level warning light on a level surface.