[Clutch Cargo]

Thanks m8s. If you hear it all the time, I should hear it at least some of the time. I shall bring this clue to the attention of my dealer.

On my older cars, I only ever heard this noise when refueling on a long road trip, due to the vacuum left by the recently-consumed fuel. But it was explained to me that the MINI has modern negative-pressure gadgetry in the fuel tank to reduce emissions. So it makes sense that the "pfft" should always be heard. If a vacuum is needed for the sending unit to work properly, replacing it won't fix my problem unless the seals are repaired too.