The mileage would need VERY careful investigation, says 65k - unlikely on a 8 year old diesel, also says new engine with 53k, so what's the total mileage.
Also, a car only needs a new engine due to lack of proper maintenance or abuse, both of which effect the rest of the car also. There are lots of 5 series about, if in doubt then buy another. You'll find a manual 5 series much harder to sell on than an automatic.