Traveling in the Jungfrau region
The region can be perfectly explored by public transport. Trains and cable cars take you to every corner of the area.
Car versus public transport
You don't need a car to get around in the Jungfrau region. From Interlaken, a car only gets you to Lauterbrunnen/Stechelberg and Grindelwald. From there, trains and cable cars take you up in the mountains. There are frequent trains from Interlaken to Grindelwald and Lauterbrunnen. Please find a comparison between modes of transport here.
The Jungfrau region is car-free beyond Grindelwald and Stechelberg (near Lauterbrunnen). The villages of Wengen, Mürren and Gimmelwald cannot be reached by car, so they're attractive to enjoy the alpine scenery without any nearby traffic.