This is one of the few myths about your car that, while based in some truth, is completely untrue for most modern cars but has truly stood the test of time.
The story we (all to often) hear goes that, as there may be sediment and rust in you fuel tank due to bad fuel at stations and rust in the tank, you should never let your car approach empty as all of the nasties will go through your fuel pump and be shot right through the engine (causing a big disaster).
However, this old wives tail doesn't take into account the 3 key advantages modern cars have due to years improvements in construction.
1. Most fuel tanks are now plastic meaning they won’t rust.
2. Most fuel pumps have very rigorous standards and have filters to remove sediment; and
3. Your car likely has 1 or 2 fuel filters that prevent rust and sediment from ever nearing your engine.
The biggest part of this puzzle is the plastic tanks which won't rust and cannot sediment themselves.
The other big aspect here is the fuel filters. As modern cars switched to using fuel injection instead of carburettors, fuels needed to be extremely clean to allow for smooth operation. Most injectors spray an incredibly fine mist of fuel at high velocity with tolerances that would never allow for any sediment fouling.
In addition to this, the fuel filters on modern cars are far better than anything that was previously available to us and often involve a strainer before the pump mechanism and an ultra-fine filter that is changed as a part of servicing to prevent sediment from approaching the engine.
In fact, in modern cars, it’s far more likely for the car not to start due to a blocked fuel filter than to have damage caused by sediment.
When taking into account this and the fact that fuel is pre-filtered before entering your car and is stored in a plastic tank that will likely not rust, the old adage of never letting your car run empty is truly a thing of the past.