As with all things. .. depends.

Many people (a majority) buy (or worse, lease) vehicles above their income level and needs for the seretonin boost and status portrayal. That aspect is clearly luxury.

But most people also need reliable transportation because the socialist government they live under isnt providing, and/or they live in suburbia where a trip to the store is miles away and not realistically viable for grocery shopping, and other routine aspects of life.

IMHO, reasonable average monthly transportation costs (including insurance, fuel, maintenance) is around gross income / 128. Using the $72000 figure for annual salary, that works out to $562/month. I know some peoples whose insurance alone will exceed that.