[14] Bmw I8 | [+] MANTIS TILLER

The 2014 BMW i3 city car and i8 sports coupe herald a bright hybrid-tech future for the BMW brand, but the next step may be delayed. The 2014 BMW i8 coupe, which we lauded as our 2014 Design of the Year, was originally thought to be introduced with a Spyder counterpart on its heels. While the drop-top i8 has not been abandoned, BMW has reportedly run into significant engineering issues that have stalled development.

According to Autocar, BMW engineers have found that the i8 coupe's carbon fiber-reinforced plastic construction is not easily compatible with a convertible variant. "The last architecture presented some fairly major challenges, to be able to produce a convertible in that format," a spokesman told Autocar. "The rigidity was hard to find with that particular architecture."

While there appears to be no set time frame for the BMW i8 Spyder's market arrival, we do know that it will at least share the same hybrid powertrain setup with its fixed-roof brother. The 2014 BMW i8 combines a 1.5-liter three-cylinder gasoline engine connected to a small generator-motor (driving the rear wheels) with a front-mounted electric motor that powers the front wheels, totaling 357 hp and 420 lb-ft of torque. The BMW i8 Spyder was first shown as a concept at the 2012 Beijing auto show.

The 2014 BMW i8 can hit 62 mph in 4.4 seconds with an average fuel economy of 94 mpg — both achieved in part thanks to the car's lightweight carbon fiber-reinforced plastic bodyshell and aluminum chassis. If this construction continues to prove difficult to translate into a two-seat convertible format, which will be shorter in wheelbase and overall length than the coupe, the BMW i8 Spyder will likely miss the 2015 production goal that the German automaker initially projected.

The 2014 BMW i8 will be available this spring, but stay tuned for more details as the timeline concerning the BMW i8 Spyder continues to take shape.