Call first, drive never
Don't start the engine. Check your rental or lease agreement for a misfuel clause — some require you to use their nominated provider, others let you arrange a drain and keep the receipt.
Avoiding extra charges
Returning a car with damage from driving on the wrong fuel is likely to be charged at dealer rates. A documented professional drain protects you.
Company cars
Tell your fleet manager. If your company has a Mr Fuel account, give us the registration and we'll bill the business directly.