Does anyone have three cars in the back of a BMW 5 series??

[FairyBasslet]

We'll have a 5 year old, almost 3 year old and new born when he/she arrives in early November. We're really keen not to change car if possible. Can it be done?

3 car seats that should read, ahem...

Sorry, I never managed it. Have had a 5 series touring for years.
Couldn't ever get even 2 boosters and 1 car seat. Fortunately I only have 2 DC, but it was rubbish when trying to give a lift home from school etc.
Unless there is such a thing as a narrow booster, otherwise you can't get near the seatbelts.
Car manufacturers dont seem to take it into account, when designing the back seats of cars.