The Porsche Panamera is all about making a good thing even better. Let’s be honest: Since its inception in 2010, the 4-door, 4-seat Panamera hatchback has been one of the very best cars in the world. In other words, Porsche could have stood pat for 2014 and still had a fighting chance against any executive-class car on the market. But that’s not how this business works, so the 2015 Panamera boasts a bunch of improvements that make it faster, roomier and generally more appealing.