Can you damage the car by driving with low fuel?

[eNCore]

I often drive the car till it has really low fuel, because I'm lazy (yeah, i know ). I always thought it didn't matter, and the worst can happen is get stranded on the road (which never happened). Recently I heard from someone/dealership that you can damage the car by driving with low fuel. Is this true?

[Netwon]

In modern cars with in tank fuel filters I think the biggest risk you have is damaging the fuel pump by running hot/overheating. If you live in a cold climate (which LA really isn't) condensation in the fuel tank can be a problem when running with a low fuel level and coming from warm garage to cold outside. This causes the fuel system the breath in some outside air (water vapour) when fuel vapors collapse/condense. I am not sure in this case what the M5's vacuum tolerance is before it "breathes in".

If I store my car (in Northern Canada M5 gets the winter off) I would always make sure she is full of fuel and ready to go in spring. For a daily driver I am sure it doesn't matter as you can enjoy your M5 year round!

[bradone1]

I heave heard that sediment can possibly accumulate at the bottom of the tank and there is the best chance of sucking it up if you run very low on fuel, possibly clogging up the filter.

Another theory is over taxing the fuel pump when its trying to suck up the bitter ends, not sure about this one though

May all be myths started by your nearest gas station

[jphughan]

Originally Posted by bradone1

I heave heard that sediment can possibly accumulate at the bottom of the tank and there is the best chance of sucking it up if you run very low on fuel, possibly clogging up the filter.

Another theory is over taxing the fuel pump when its trying to suck up the bitter ends, not sure about this one though

May all be myths started by your nearest gas station

I've heard the sediment theory but I'm not sure how you'd be more likely to suck up sediment when the tank is close to empty than when it's full, unless the suction hose just floats around in the tank? I don't know a lot about fuel system design.

But OP, as has already been mentioned, in our cars the fuel pumps sit inside the tank itself, and they rely on being submerged in fuel in order to stay cool. So if you were driving the car hard in hot weather on a low tank, yes it could overheat.

[stealth.pilot]

How low? Less than one gallon left?

[ColdList]

This is worrying about nothing. You would run out of gas prior to doing damage. The old "sediment in the tank" myth has been floating around since I was a teenager. Not gonna happen. Fuel draws form the bottom all the time. One thing I have learned is that if you hear it form the dealership you pretty much can ignore it.

[eNCore]

Originally Posted by stealth.pilot

How low? Less than one gallon left?

Since I pumped 20.X gallons of fuel into the car and the car has a 21.1 gallon tank, I would say yes or very close.

[bimmer-boy]

heard the sediment theory too, tbh heard it sits at the bottem so when fuel runs low thats when its most likily to mix with it as it sits at the bottem.
however in my experience with general cars never had the issue and i run them in the reserve regularly on occasions, so wouldnt think the new m5 would be any different.

as for the cold and running it in the reserve, it did cause a slight breathing issue on my e46, as air/condensation got into the fuel tank when it snowed here for a week and temp drop.

my advice.. its a m5, fill it up so you can keep driving it !

[stealth.pilot]

I would think that if sediment is an issue, then it will also be an issue immediately after filling since the flow of fuel in will cause the sediment to rise due to circulation currents in freshly pumped fluid. While the sediment will settle over say the next 10 minutes, sediment could flow into the engine if you turn the engine on immediately after fueling.

Since the above is not an issue, I assume the fuel is filtered out of the tank.

[stealth.pilot]

Originally Posted by eNCore

Since I pumped 20.X gallons of fuel into the car and the car has a 21.1 gallon tank, I would say yes or very close.

Interesting. I don't think I've ever pumped more than 19.x so you must have been running on E for a while!