If you elect to travel by car you must leave it in Lauterbrunnen where there is a multi-storey covered car park. Onward travel to Wengen is by train from the adjacent railway station and the journey time is about 15 minutes.
International train connections will take you to Interlaken Ost station where you will change to the regional railway, the Bernese Oberlandbahn, for onward travel to Lauterbrunnen and Wengen. The total journey time from Interlaken Ost is about 45 minutes.
Lauterbrunnen, and Wengen, are reached by train from many international airports in Switzerland. Journey times to Wengen are approximately:
Bern Belp Airport 2.75 hours
Basel Euro Airport 3.5 hours
Geneva Airport 4.25 hours
Zürich Kloten Airport 3.25 hours