A pre-production prototype believed to be the upcoming Porsche Cayenne Coupe has been spied again, this time during cold weather testing in Europe.

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Despite the Panamera shell, this development vehicle is shorter, wider and noticeably higher than the Panamera, expected to be an early mule for the swoopy-styled version of Porsche's large SUV.

When it hits showrooms, likely sometime over the two years, the Cayenne Coupe will take on the likes of the BMW X6, Mercedes-Benz GLE Coupe and upcoming Range Rover Sport Coupe.

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It's believed engine and transmission options will largely mirror those offered in the next-generation Porsche Cayenne which has also been spied testing in recent months, including a range of turbocharged six- and eight-cylinder petrol and diesel engines.

According to spy photographers, this test vehicle didn't make any normal engine noise, leading us to believe there could also be a plug-in hybrid variant (like the current Cayenne S E-Hybrid) and/or even a fully-electric model in the works - further highlighted by the electric warning stickers scattered around the mule's body.

There has been speculation that an all-electric Cayenne Coupe will be based on the technology of the production version of the Mission E concept, which will be launched before the turn of the decade.

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Timing for the Cayenne Coupe is still unknown, but considering the wagon is expected to make its debut sometime this year, it's likely the coupe version won't be revealed until 2018, with first deliveries arriving later that year or even early-2019.

Stay tuned to CarAdvice for more updates.