Opel is testing the seventh-generation Astra ahead of its projected launch in 2015. Wheels24's spy photographers captured images of the popular hatchback.The Astra will ride on a revised version of General Motors’ D2XX global vehicle architecture which will also underpin the next Opel Volt and Ampera and Chevrolet's Cruze. Although covered in camouflage, the prototype in our gallery images gives a clear idea of what to expect from the next Astra.IMAGE GALLERY: 2014 Opel Astra (Spy)The model spotted in these spy images appears to be larger than the current Astra. You can also seenew external mirrors-mirrors and the rear has a more prominent hatch and a longer spoiler. The overall design will be influenced by the Monza concept.Following the trend set by VW’s Golf 7 and Peugeot’s 308, most of the automaker’s efforts will be focused on weight-reduction (as much as 50-100kg, depending on model). Power will be provided by a new turbocharged family of three and four-cylinder engines, as used in the new Adam.Opel could introduce the next Astra at the 2015 Geneva auto show in March or in September at the 2015 Frankfurt International Automobile Exhibition.