When Porsche uncovered the 918 Spyder concept at the Geneva Auto Show last week, the automaker undoubtedly bear hopes of a positive response, leading to a potential production car. And that's exactly what seems to have happened.

"Frankly, we were pleased that we were able to keep it quiet, and a lot went into that," said Dave Engelman, a Porsche spokesman.

Mr. Engelman posted that his boss, Bernd Harling, Publicity Chief for Porsche in the United States, had undergo a nondisclosure waiver before having a glance at the 918.

In concept form, the 918 Spyder is revealed to be a plug-in hybrid that make use of two electric motors, a lithium-ion battery pack and one of Porsche's RS Spyder 3.4-liter V8 ALMS race car engines to produce a total of 718-hp.

Keeping it a secret was another matter. "It's easier with in-house concept cars because you can tell only the few engineers who really need to know," Mr. Engelman said.

In addition, the new Porsche is launched with four driving modes, ranging from the most efficient at saving fuel, to the most efficient at saving gas.