BERLIN (Reuters) - Porsche expects to increase sales of the redesigned Panamera sedan by at least a third next year, its chief executive said, counting on enhanced digital features and more efficient engines to boost demand for the 113,000-euro ($125,000) model.

Volkswagen <VOWG_p.DE>-owned Porsche is targeting luxury-car buyers with a sportier, sleeker version of the four-door Panamera that is due to hit European showrooms in November and Chinese dealerships early next year.

To tap growth in its largest market, Porsche will offer an extended version to Chinese buyers - many of whom have drivers - which is 15 centimeters (6 inches) longer than the standard model, Chief Executive Oliver Blume told reporters on Tuesday.

"China is still on a high level, though not where it was two to three years ago," Blume said during the model's unveiling in Berlin.

"We expect (global) sales to be slightly above the level" of 20,000 cars per year originally targeted for the Panamera when it was launched in 2009, he said. A total of 15,004 of the cars were sold last year.

Forecasts by research firm IHS Automotive suggest the CEO could be more upbeat.

Sales of the Panamera, which saves costs by sharing a platform with models from Volkswagen's (VW) Audi and Bentley brands, may more than double to 35,444 cars by 2020, IHS predicts.

By comparison, BMW's <BMWG.DE> 7-Series model may increase 30 percent to 51,825 cars while sales of Mercedes' <DAIGn.DE> S-Class may decline 21 percent to 79,044 units.

Porsche, a key contributor to VW group profit, drew fire from industry observers for the first-generation Panamera which it launched during the 2009 financial crisis when premium-car buyers withheld spending.

With its disproportionately long midsection and a humped up rear roofline, it was difficult to recognize the 2009 Panamera as a Porsche. The successor model, which boasts an infrared camera-based night vision device, comes with a rear roofline 2 centimeters lower.

"The concept (of the Panamera) required a lot of courage and many said we were crazy," Blume said. "But courage changes everything."

Despite parent VW's diesel emissions scandal, there were no discussions among top managers at the group to discontinue the Panamera's diesel version which surges to 100 kilometers an hour in 4.5 seconds.

"Today there are still many markets where diesel is indispensable to fulfill CO2 limits," Blume said. "In the U.S. there are still many friends of diesel who appreciate the long-distance range."

(Reporting by Andreas Cremer; Editing by Chris Reese)