The Porsche 356 Cabrio 1.1 40HP quite much loses with the BMW Z4 E85 Cabrio in the category of horsepower having them by 110 hp less. Therefore the engine of the BMW produces lots of power and good acceleration.
The BMW has 405 mm longer wheelbase than Porsche 356. Therefore the BMW Z4 E85 is more safe and has a better stability. Besides, longer wheelbase has impact on convenient and more comfortable riding.
The BMW Z4 E85 Cabrio is 139 mm longer in relation to the Porsche 356 Cabrio. Long cars more of passenger space and in most cases provide more storage space. While the BMW seems to be better for families or persons who value comfortable rides, the Porsche 356 may appeal to women because it will not make troubles with parking and will be more maneuverable.
If you are a tall driver or you tend to carry in the trunk stuffs of big size, the BMW, which is by 22 mm higher than the Porsche, is better choice for you. However, presented cars do not vary much it the aspect of its height and it should not be much noticeable.