I know The Barrister has fond memories of the old Bar Cars on The New York, New Haven, and Hartford Railroad (now Metro-North). I have some such memories, also.
People smoking and drinking Scotch, and the bow-tied, white-jacketed bartender who knew everybody's choice. A cozy cheerful place on the 6:14 from Grand Central. A smoke-filled decompression chamber between work and home.
The famously alcohol-fueled and adultery-fueled bar car on the branch line from Stamford up to New Canaan and Ridgefield, CT used to have their own web site, but I can't find it now.
Photo below from the NYT photo essay. I never saw a bar car like that one, though. In my time, usually more packed with people (including chic gals and MILFs on their way home from shopping and hair-dos at Kenneth's) and so full of fragrant and wholesome tobacco smoke that you couldn't see from one end to the other.
Addendum: A reader has kindly sent us a Bar Car site