BMW Toyota sports car images | report

Toyota’s FT-1 concept was arguably the star of the 2014 Detroit motor show -- prompting considerable comment about whether or not it points to a successor for the iconic Supra – with an outright performance focus to tackle the Nissan GT-R head-on.

But there's perhaps even stronger interest in the next sports car project, for which the Japanese company is teaming with German luxury brand BMW, with the two brands inking a deal as the year closed.

A new report by Japan's Holiday Auto magazine has explored what the result of that union could look like – and what could be under the skin.

Holiday Auto has rendered what it believes the Toyota model will look like, with classic open roof and long-nose short tail proportions, and Toyota-influenced details and speedster-style rear end with twin headrest fairings. The rendering’s pronounced wheel-arches and arcing rear quarters are also reminiscent of the Audi TT.

Speaking with an anonymous insider, the report suggests that the BMW half of the project will result in the next-generation Z4 roadster, using a similar aluminium and carbon fibre structure to the new BMW i3 and i8 to reduce weight.

“At least the drive system must be front-engined/rear-drive as BMW wants to focus mainly on the next generation Z4. Therefore, BMW will design the main body basics and probably manufacture it as well,” the report cites the insider as saying.

The report suggests that despite the shift to more exotic materials, the next BMW Z4 will cost no more than the $77,500-$120,000 steel-based chassis current model, thanks to the production-friendly resin-transfer moulding (RTM) composite technology pioneered by the i3 and i8.  

The memorandum of understanding between the two brands has highlighted that Toyota’s hybrid drivetrain prowess will be the Japanese giant’s key contribution to the project, and the article elaborates that a new system using capacitor energy storage similar to Toyota’s TS030 LeMans racer and the Yaris Hybrid R concept from last year’s Frankfurt show will reportedly feature. 

However, the BMW/Toyota sports car’s system is likely to be significantly scaled down from the racer and concept, as Toyota 86 chief engineer Tetsuya Tada suggested to Carsguide last year that their supercapacitor-based setup would be cost prohibitive for road-going models.

Generating sufficient charge for capacitors is also a challenge under typical road-driving conditions, and the report suggests a road-friendly and cheaper nickel-metal hydride or lithium-ion battery -- as used by existing Prius models -- is likely to be paired with capacitors.

As for the combustion element of the hybrid setup, it’s tipped that BMW will to contribute a petrol-fuelled engine from its catalog of powerplants. “It is unlikely that a Toyota engine will be used, because BMW will not accept to use Toyota’s components for all principal components,” Holiday Auto’s source says.

Toyota has demonstrated a willingness to use power sources from other brands of late, with the Subaru-based 2.0-litre boxer from the 86 sports coupe, and the use of BMW-designed 1.6-litre diesel engines for the Corolla-based Verso people mover in Europe.

These reporters are on Twitter: @Mal_Flynn @KarlaPincott