Our eagle-eyed spies are at it again and this time they caught something very interesting: the next generation BMW Z4 and Toyota Supra undergoing testing... together.

As we had reported several times before, BMW and Toyota have joined forces to co-develop two of their most famous and most exhilarating models: the Z4 and the all-new Toyota Supra, respectively. And here is the proof of that collaboration, with the two cars side-by-side and fully camouflaged. 

Spied: 2019 BMW Z4 shows curvaceous body amidst camouflage

Our photographer, however, focused more on the Z4, BMW's vision of an all-new two-seater roadster that is just about ready to hit production.

What's noticeable on the camouflaged roadster is its more striking kidney grill. Compared to current BMWs, the Z4 appears to have an evolutionary redesign. Side-by-side with the Concept Z4 (which previews the upcoming roadster), shown last year, it looks like the production version will stay true to the concept's design.

Spied: 2019 BMW Z4 shows curvaceous body amidst camouflage

With a long hood and short deck design, the next-gen Z4 also appears to take inspiration from grand tourers and coupes. Meanwhile, the angular taillights and sharp-looking headlights give the Z4 a modern and aggressive look. Also curious to see at the rear of the Z4 is what looks like a integrated spoiler on the trunk lid which also comes with a third LED brakelight.

While both the Supra and Z4 will have the same platform and powertrain options from the collaboration, the two cars differ greatly in terms of styling. Plus, the Supra will only be availale as a hardtop coupe while the Z4 can only be had as a soft top roadster; at least for now.

Spied: 2019 BMW Z4 shows curvaceous body amidst camouflage

When officially launched, both the Z4 and Supra will apparently be available with four- or six-cylinder TwinPower Turbo engines. The entry-level offering will supposedly have the 2.0-liter B38 inline-four that will put out 192 PS with 280 Nm of torque. Next up is the midrange 2.0-liter codenamed the B48 which produces 251 PS and 336 Nm of torque. The top-of-the-line variant will come with a 3.0-liter inline-six known as the B58. The six-cylinder is expected to produce 340 PS and 500 Nm of torque.

Both cars are expected to make their public debut sometime in late 2018 or in early 2019. There is a lot of hype surrounding the joint project after the success of the Toyota/Subaru collaboration that produced the 86/BRZ.