The express train D 92/93 "Bavaria" was running between Munich and Zürich as far back as the Fifties. With the start of the winter schedule in 1969 on September 28 the "Bavaria" was transformed into the TEE 55/56 with first class seating only in order to offer an attractive train for the business passengers between Munich and Switzerland's banking and trade center. With the increase in TEE traffic between Munich and Zürich the travel time could by reduced by just an hour compared to the previous express train connections – an impressive reduction in running time for this route with its difficult grades and lack of electrification in the DB area.
Initially, the Swiss four-part TEE diesel powered rail car trains, classes RAm 501 and 502, were used, but this came to an abrupt end after the notorious railroad catastrophe at Aitrang on February 9, 1971. At that time the TEE 56 "flew" on its run from Munich to Zürich behind the Aitrang station in a sharp right hand curve with the cab control in the front at about 130 km/h / 81 mph from the tracks. The speed limit at this location was only 80 km/h / 50 mph. Due to the destruction of the TEE powered rail car train, a locomotive-hauled train of cars ran starting on Februar 16, 1971. The DB provided a compartment car (Avümh 111) and an open seating car (Apümh 121); an SBB RIC design dining car (WRm) supplemented the train. Initially, the dining car still ran in its red paint scheme, but it was soon painted in the TEE scheme. Starting with the summer schedule for 1971 the pair of trains ran as TEE 66/67.
A class 210 gas turbine locomotive pulled the "Bavaria" in the non-electrified DB section Munich - Kempten - Lindau. Between Lindau and St. Margarethen the venerable ÖBB class 1180 electric locomotives with side rods initially reached TEE status until the Swiss Federal Railways (SBB/CFF/FFS) powered the "Bavaria" all the way between Lindau and Zürich with class Re 4/4 II locomotives in order to save the change of locomotives in St. Margarethen. Due to the wide zig-zag of the catenary wires on the short electrified DB section and on the Austrian part of the route, the Swiss used locomotives with the road numbers 11196 to 11201 which had been equipped with a pantograph with a wider contact strip for the cross border traffic to Lindau. Starting in the summer of 1972, the Re 4/4 I units in TEE colors with road numbers 10033 and 10034 became the motive power for the "Bavaria" out of Lindau. These locomotives also have a pantograph with a DB/ÖBB contact strip for the section of the route Lindau - St. Margarethen.
On May 21, 1977 the "Bavaria" ran for the last time as a TEE. It was replaced with the start of the summer schedule for 1977 by the two-class express train pair D 266/D 267. The "Bavaria" experienced a new promotion – this time to EuroCity status – with the schedule change for 1987/88. Starting on May 24, 1987, it ran for the next 15 years as EC 98/99. This name with its rich tradition disappeared on December 14, 2002 when this pair of trains was discontinued.