Am almost amazed by this. Went to get a car seat from the garage the other day, to find two boosters and one car seat covered in mould. It was only surface stuff, so a wash of the covers, and they're all sorted. However, the straps of the car seat had mildew in them too. I have never before got this out. Realised it was because I used it for a friends child, who is a dribbler\drink spiller, and didn't dry it before putting back in the garage.
So, antibac sprayed them. No difference. Toothbrushed them with a solution of mild bleach and washing powder. No difference. Overnight soak in very strong washing powder solution. Like new V.impressed. They're now in the washing machine for a good wash, and the car seat will be like new. And will not go back in the garage!!!
Happy FourArms!