I have a third kid on the way so I will soon have a 4 year old, 2 year old and newborn. I currently have an E350 and do not think I will be able to fit 2 car seats and a booster seat. Does anyone have any experience with this? The rear seat in an S550 is only 1.5" wider than the E350. Would this extra 1.5" make much of a difference? The rear seat width in other large luxury sedans 750, A8 and the american luxury sedans are roughly the same as the S550. I would be looking for a 3 year old model for around 45k. Any suggestions would be appreciated. I do not want to have to switch to an SUV with 3 rows.