We've got a 30d X3, previously had the 20d which was adequate but felt it was a bit under powered for the size/weight.
The 30d is plenty good enough.
It's not a sports car but sub 6-sec to 60 for something this size is easily fast enough.
Plenty of torque for overtaking
For the size we're pleased with the fuel consumption - we've had ours from new and fuel economy improved markedly after around 15k, we now average around 33mpg in town but can see 50+mpg on long runs.
The MSport and above are fairly well spec'd but options worth having are
- Electric seats (Cindy and I both use the same seat position but the memory will be useful if you and Donna have different seating positions)
- LED headlights (the auto high beam and beam splitting are great)
- Extended storage (comes with rails in the boot and removable metal 'loops' that slide up & down the rails to provide tie points
- 40:20:40 split rear seats
We didn't bother with any of the audio upgrades as Cindy only listens to the radio and I've got tinnitus in my left ear so it's be wasted on me now.
I'd say think about what it's going to be used for - ours is a daily driver and luggage hauler, it's nice and comfortable and a pleasure to drive but it's not (and never will be) a sports car, so options like adjustable dampers and performance brakes are, to me at least, a bit unwarranted and will only become expensive items to repair/replace in the future.