BMW issued a recall on the Z4 model

Certain vehicles contain a defect involving the electric fuel pump. Under certain environmental conditions, for example, driving during high outside temperatures in combination with high altitudes (over 5,000ft.), vapor lock in the fuel pump could occur. This could cause the engine to stall. If this were to happen, the engine could be unable to be restarted for approximately 15 to 20 minutes. Correction: Dealer will install a resistor in the electrical line leading to the fuel pump. This will reduce the power output of the fuel pump and preclude an occurrence of vapor lock.