Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. The MINI Cooper is significantly cheaper to get to the dealership than the BMW Z4.
The MINI Cooper is tremendously less pricey than the BMW Z4 in terms of MSRP.
Utility
Drivers with frequent kid-duty might favor the MINI Cooper over the BMW.
The MINI Cooper is a better choice than the BMW Z4 with respect to hauling capacity, especially if you often need to carry a lot of suitcases or large animals.
Comfort
While the front cabin in the BMW Z4 offers a bit more head room than the Cooper, there really isn't much of a difference.
Dimensions
The BMW Z4 is tremendously heavier than the Cooper.
The MINI Cooper's tank is about the same size as the BMW Z4's, though the BMW Z4's is a little larger.
The MINI Cooper fits in smaller parking spaces than the Z4.
Performance
With that kind of horsepower, the BMW Z4 is a true speedster.
Regarding horsepower, the Z4 packs quite a punch and will knock the MINI Cooper down a few rungs. On the flip side, keep in mind that high horsepower engines often command higher insurance premiums.
Drivetrain
The MINI Cooper's engine is tremendously smaller than the Z4's. Note that smaller engines can be stressed more; on the other hand, smaller engines are often cheaper to fix.
Torque equals pickup, and the BMW Z4 will have picked up and gone by the time the MINI Cooper finally gets moving.
The BMW Z4 packs quite a punch compared to the MINI Cooper when it comes to torque, which is roughly equivalent to acceleration.
Overview
The BMW Z4 and the MINI Cooper have the same basic warranty.