Friday afternoon car
A faulty or sub-standard car. More widely, any poor effort.
This is a British phrase and alludes to the belief that car workers lose interest toward the end of the week and make cars which are below standard. The first reference I can find to it is in the Usenet group 'net.auto', from August 18th 1983 ( at 5:54 pm if you want to be precise):
"Regarding the British car which leaked more oil ... Some of my (British) friends would say you have a "Friday afternoon car" - one built on the last day when everyone's in a hurry to go home."