I purchased the Britax Brownstone Parkway in April of 2007.  I drive a Yukon XL, so my Britax Marathon car seats fit fine.  When our oldest daughter got a car, we had to purchase booster seats, as the Marathons were way too wide for 3 of them to fit in the back of her Infiniti G35.  With 1 Marathon in the middle, we could place 2 Parkways to fit on either side of the Marathon, although it was a tight fit.  After about a month, the elastics on the head rest portion of the booster came off, so when we put their seat belts on, the fabric was loose and would no longer cover the styrofoam. Without...