The Mini Cooper has a small boot: 210 L behind the rear seats on the 3-door petrol. The petrol F66 and the electric J01 are built on different platforms with different boot shapes, so match a kit to the powertrain, not just the badge.
Three products we would look at first in this category. Fit for your Mini still comes first: check the compatibility list on the listing against your exact model and year, and read the model guide above.
NOCOBoost Plus GB40 Jump Starter
1000A lithium jump starter for petrol engines up to 6.0 L.