Getting to Garmisch-Partenkirchen: the train is genuinely the easier option.
Garmisch-Partenkirchen has its own railway station with frequent direct connections to Munich, and every attraction on this site — the Zugspitze ascents, the Eibsee, the Partnachklamm, the Reintal trailhead — is reachable on foot or by local bus from that station. Unless you're planning to explore well beyond the valley, a rental car adds cost and parking hassle without adding much.
By train from Munich
Deutsche Bahn runs direct services between Munich Hauptbahnhof and Garmisch-Partenkirchen, with the fastest journeys around 70 minutes and typical journeys closer to 80–85 minutes depending on the service type (regional versus faster long-distance trains). With roughly 22–23 direct departures a day, there's no need to plan around a sparse timetable — this genuinely works as a same-day trip from Munich if you want to keep a Munich base for the rest of your visit.
By car
The drive from Munich is roughly 90 km, mostly via the A95 motorway, typically taking a little over an hour outside peak traffic. A car is genuinely useful if you want to explore beyond the immediate valley — into the wider Werdenfelser Land region, or across the border into nearby Austria — but adds parking costs at the more popular trailheads and lake car parks, which fill early in summer.
From Munich Airport specifically
Munich Airport (MUC) doesn't have a direct train to Garmisch-Partenkirchen — plan on a connection through Munich Hauptbahnhof (via the S-Bahn into the city, then the direct regional service onward), or a direct transfer/rental car, bringing the total trip to roughly 1.5–2 hours depending on connections. Build this into your first-day schedule rather than assuming a same-day mountain ascent right after landing.
Getting around once you're there
Garmisch-Partenkirchen's own railway station is also the starting point for the Zugspitzbahn cogwheel train (see the cogwheel train page), and local buses connect the station to the Partnachklamm entrance, the Wank cable car base, and the Garmisch-Classic lift stations. Most first-time visitors genuinely don't need a car for the core sights covered on this site — save it for side trips further afield.