The guys at Auto Express have got their hands on some recent BMW Z4 spy photos. The first photo is a prototype and you can clearly see that the soft rooftop has been replaced by a metal folding top, similar to the one found in the E93 3 Series Convertible.
We have mentioned before that the 2009 BMW Z4 will be powered by the same engine found in the 135i and 335i models, more specifically, the twin-turbo 3.0-liter. We also agree with the Auto Express folks on the idea that the Z4 will probably get a diesel engine as well, somewhere down the road.
Since BMW is actively pushing their EfficientDynamics technology, we believe that the new Z4 will be taking advantage of that program.