I've had three different, but somewhat related, experiences with my 2004 M3 "running out of gas" when the gas gauge still showed about 1/4 tank of fuel. Two of the three incidents occurred at highway speed. With no warning, the engine began to sputter, loose power and die after coming to a stop. When gas was added, it idled rough and appeared to be in "limp mode". After limping to the nearest gas station, a fill-up proved there had been about 5 gallons in the tank when the incident occurred. Another common symptom is the "Service Engine Soon" warning light. In one case, the EML light came on too. After filling up with gas, the engine seems to be fine. The dealership service techs are stumped because they can't replicate the fault. Does anyone have any idea why the car would appear to run out of gas when, in fact, the tank is not empty?
The dealership kept the car for almost two weeks ... a tech drove it regularly intent on duplicating "the fault" ... finally, he, too, ran out of gas with gas in the tank ... turns out BOTH sending units in the tank were bad ... they replaced both units and the fuel pump under CPO warrantee ... haven't had a recurrence of any of the symptoms but I'm still wary when the gauge gets below half full.
