Anyone any ideas why after a distance of about 5 miles, when I pull up, I get what smells like exhaust fumes coming through the heater vent in my 5 series BMW 52 plate. If I go on a long journey say 100 miles and pull up, then a thick cloud of blue smoke fills the cab. When moving there is nothing, only when pulling up. Filters clean, and no exhaust leaks.
you have an exhaust leak somewhere, the fumes are making there way into the heater/vent intake. Probably a small leak that only becomes apparent when hot, ie, expansion. Probably repairable with exhaust paste once you find the leak. Run it in the drive till it happens and have a look round, if you can get it on blocks first you should be able to look round the whole system.