A poorly built automobile. A piece of junk. The reason behind the name "
Friday" is that workers typically had a long week, are tired, and are looking forward to the weekend... therefore, they are a lot more careless with the construction of the vehicle, lending to it's numerous problems.
This typically applies to a make/model of vehicle that is usually of pretty good quality, and the "
Friday car" is more the exception than the rule.
Really bad cars can be referred to as "
Friday afternoon at 4pm before a three day weekend car".