We reused the car seat we got from Mercedes for our E class we had. It's called Mercedes Duo Plus but it's actually made by Britax for Mercedes. It is a European Model. It is a convertible car seat that fits up to 70 lbs. I like how it is compact and not too high.
My wife's X5 has the Britax Frontier 85.
2013 BMW X5 35i
Alpine White | Cinnamon Brown | M Sport
2013 BMW 550i
Titanium Silver | Black | M Sport