I’ll give an example I saw recently to clear things up. Hope this helps. First are the two claims.
1. In a married pair train set on the L, the even numbered car is the higher numbered car.
✅ Yes, that is true. Like 3457-3458 and 3201-3202 for example.
2. In service, even numbered cars always face one direction and odd numbered cars face another direction.
❌ This is false. While driving on the Kennedy I saw an eight car set of 2600s heading towards Forest Park. Some of the leading cars in the set were even numbered cars and some of the cars were odd numbered cars. This probably happened as a result of cars moving around the system over the years, and what the train did when it reached the end of the line. For example, at O’Hare, to change directions, the train operator must leave the cab at the front of the train and go to the cab at the rear of the train, turning that cab the new front of the train, where at Forest Park, he or she also has the option of looping around the yard and returning to the station without changing cabs.