Quite apart from its breathtaking design, the vehicle body of the new Mercedes CLS spoils all occupants with its generous interior measurements: in particular, the four-door coupé offers more elbow room (8/21 millimetres at the front/back) and more shoulder room (21/13 millimetres) than its predecessor. The starting point for this extra space was the vehicle body, which is 29 millimetres longer, 13 millimetres higher and 8 millimetres wider than its predecessor. The wheelbase has increased too, by 20 millimetres to 2874 millimetres.

The boot has a capacity of 520 litres and, for the first time in the Mercedes-Benz CLS-Class, comes with EASY-PACK quickfold as an optional extra for the rear seat backrest which folds down in a 1/3:2/3 proportion. Up to 19 different places to store and secure objects throughout the car make it quick and easy to accommodate smaller objects. The EASY-PACK comfort box for the boot, which is an optional extra, provides even more stowage space. It is normally folded flat and stored under the parcel shelf. If the EASY-PACK comfort box is needed, it can be pulled out and folded down. Thanks to its flexible base, its volume can be varied from 7 to 55 litres. Its can bear a maximum of ten kilograms in weight. The box, which is some 530 millimetres wide, can be removed from the boot without the need for tools if its full capacity is required.