It won't surprise you to learn that from the front bumper to the B-pillar, the 3 Series Touring is identical to the saloon model. This version of this estate variant has larger exterior dimensions than its predecessor. It has grown by 76mm to 4,709mm in length, by 16mm to 1,827mm in width and by 11mm to 1,440mm in height. The wheelbase has also been extended by 41mm to 2,851mm, plus 43mm has been added to the front track (1,587 mm) and 21mm to the rear track (1,604mm).
You'll want to know about the boot, accessed via a standard powered tailgate. It's 500-litres inside (5-litres bigger than the previous generation Touring model and 20-litres bigger than the boot of a current 'G20'-generation 3 Series saloon model. The capacity falls a bit with the 330e PHEV variant due to the battery placement beneath the floor. BMW reckons those stats don't tell the whole story, pointing out that the boot is up to 112mm wider than the predecessor design and its loading aperture is 30mm higher and up to 125mm wider in its upper section. The loading sill is slightly lower (at 616mm) and the step between it and the boot floor has been reduced in height from 35mm to 8mm - all of which makes it much easier to load large, heavy items of luggage. Fold the seats flat and there's a maximum capacity of 1,500-litres.