Porsche's V8-electric hybrid offers speed and efficiency in spades.

The rumors were accurate: Porsche has introduced a second plug-in hybrid variant of the new Panamera powered by a turbocharged V8 engine. The model will debut next month at the Geneva Auto Show. The Panamera Turbo S E-Hybrid's 550-horsepower V8 works with an electric motor rated at 136 horsepower. The two power sources generate a combined output of 680 horsepower and 626 pound-feet of torque. An eight-speed dual-clutch automatic transmission channels all that grunt to the four wheels.

With both the V8 and the motor running, the Panamera hits 62 mph from a stop in 3.4 seconds, and it goes on to a top speed of nearly 200 mph. A torque vectoring system, an air suspension on both axles, and carbon composite brakes let the driver make the most of the hybrid setup's output.

Alternatively, a 14.1-kWh lithium-ion battery pack stores enough electricity to power the sedan for 31 miles. A full charge takes six hours when using a standard charger, or 2.4 hours when using a quick charger. A smartphone application lets users monitor the charging process remotely.

The Turbo S E-Hybrid is nearly identical to the other Panamera variants. However, careful observers will notice it rides on specific 21-inch alloy wheels. Inside, there's a hybrid-specific instrument cluster.

The Porsche Panamera Turbo S E-Hybrid will go on sale in Europe in July, and in other markets such as the United States and China before the end of the year. Buyers will be asked to choose between a model with a standard wheelbase, and a long-wheelbase model named Executive.