Many owners (not me though, I confess) have been troubled by exhaust fume smell in the cab when one or both of the front windows are open. Two options for you here .
Fred (Fred & Gill) has discovered that a short length of decorative tailpipe trim, that extends the exhaust pipe beyond the bodywork, works wonders and totally cured his problem. Others have also reported good results from doing this.
The ‘fridge housing can be another source of fumes into the habitation area, as it was in my case. The ‘fridge should, from new, have had a sealing strip fitted that entirely sealed the perimeter of the ‘fridge. If this strip is missing, badly fitted or damaged, it will permit a sizeable draught to enter. It could also permit exhaust and burnt gas fumes to enter too, so it’s important to effect a cure.
There are several ways to effect a repair – the most professional is to purchase a new seal appropriate to the ‘fridge, remove the ‘fridge from the housing and refit with the new seal. Or you could just pull the ‘fridge out a bit, repair the existing seal and push the ‘fridge back. Or, simplest of all, just inject sealant from a nozzle gun into the crack all round the fridge.