It feels like BMW has been testing the next-generation Z4 since forever and as such we can all agree that an official reveal can’t come soon enough. While we’re patiently waiting for the roadster’s big debut, prototypes are temporarily based at the Nürburgring to undergo final testing in order to work out the kinks until the highly anticipated premiere.

A new spy video has emerged and it shows a couple of test vehicles doing their thing at the Green Hell. While you can’t never be too sure regarding the exact identity of work-in-progress vehicles, our hunch is that BMW was evaluating a spicier flavor of the Z4, particularly the M40i. Latest reports are indicating it will offer somewhere in the region of 335 hp in basic specification and up to 385 hp in a beefier configuration. Regardless of output, the Z4 M40i will be top dog in the roadster’s lineup as BMW has made it crystal clear it won’t do a full-fat M car.

Those not willing to pony up more dough for the flagship version will have to settle for lesser versions of the Z4, such as an s20i model equipped with a smaller four-cylinder mill good for about 180 hp. The same 2.0-liter unit will also find its way inside the Z4 s30i where it will push out 250 hp.

We’ve attached our most recent batch of spy shots showing a different prototype that was caught off-guard by our spies, showing a great deal of the Z4’s cabin with its swanky new digital instrument cluster accompanied by BMW’s latest iDrive.

As a refresher, the BMW Z4 is expected to share the assembly line with the new Toyota Supra in Graz, Austria at Magna Steyr’s plant where the two will be manufactured following their debuts slated to occur in the latter half of 2018. The first to come out will probably be the Z4 as latest intel suggest the soft-top roadster will go official at a dedicated event this summer before heading to the Paris Motor Show.

Video: Automotive Mike / YouTube