I was deep into locating a tumbler for my wife so she would give up on the open top plastic cup while driving. I stumbled on this one and it had all the makings of a good one.
Small enough to fit in a cup holder
16oz
Vaccuum walled
Stainless construction.
Servicable top that can be cleaned.
Only issue reported was that it can be hard to determine the correct side to drink from and if you get it wrong it pours the drink on your face.