Volkswagen has revealed the first technical details of the new Passat saloon and estate, ahead of the cars' unveiling in July and their public premiere at the Paris Motor Show in October.

The eighth-generation Passat is up to 85kg lighter than its predecessor, helping it to claim expected fuel-efficiency improvements of up to 20%.

Despite exterior dimensions that are marginally smaller than those of the previous Passat, interior space is improved, with more leg and head-room, as well as increased luggage space.

A highlight of the Passat's new range of engines is a high-performance, four-cylinder, 2.0-litre, bi-turbo diesel delivering 238bhp and 500Nm from 1,750rpm.

This engine will be available only with a new seven-speed DSG gearbox and 4Motion all-wheel drive.

A plug-in hybrid model will also be offered, with the potential to travel 31 miles on battery power alone, and with a potential maximum range of around 600 miles.

Other new technology offered includes the 'active info display', which replaces the instrument cluster with a fully configurable interactive 12.3-inch display; a heads-up display; the latest 'modular infotainment system', including the Car-Net remote app; a further-developed 360-degree area view function; and the latest generation of park assist.

The latter includes the option for the car to park itself forwards into perpendicular spaces - useful, for example at supermarket car parks, where access to the boot is important. It also includes a world-first trailer assist, which provides help when reversing a vehicle with a trailer attached - without the need for any modification or adaptation of the trailer.

Other safety technology includes side assist with rear traffic alert; traffic jam assist which makes stop-and-go driving more comfortable; emergency assist, which can potentially halt a vehicle when the driver is incapacitated; and the latest front assist system with city emergency braking, which optionally combines both radar and camera sensors to add pedestrian detection.

New Passats will feature LED tail lights, with halogen or LED headlights. Together with dynamic light assist, one of the two LED headlight options automatically adjusts the beam for maximum illumination of the road without dazzling other traffic.

Further details and first pictures of the Passat will be available in early July, ahead of the Paris Motor Show. UK sales will start before the end of the year, with first deliveries expected in early 2015.