Update....
Definitely no mammels inside the car. Smell comes from steering wheel, sort of like puke.
Pulled the steering wheel (thanx, Hemi), put it in dish washer and got yelled at from wife (she had all rights to do so, the smell went into the dish washer and it took several empty runs to get it out again, so DON´T do that). The smell on the steering wheel was still there, but at least all the dirt, that built up over the decades, was gone. The plastic turned whitish/foggy and developed some ugly gray stains, probably from where the remaining water dried up in the dish washer, so again, DON´T put the steering wheel in the dish washer. I then painted the wheel with two thin coats of matt black and now I am still in the process of putting on some coats of clear.
Will this cure the problem? I don´t know. I did expect the smell to vaish by the time I put on the base coat, but everytime I enter the garage I can still notice it slightly. I might end up buying a repro steering wheel and even if they are in the threehundreds I probably would have been better off doing this in the first place. Is CJ a decent place to buy?