Invitation for Bid (IFB)
The sealed competitive process used when an agency knows exactly what it wants and is selecting on price. The standard route for buying vehicles.
An invitation for bid publishes a specification, takes sealed bids, opens them publicly and awards on price to whoever is responsive and responsible. It is the default method for buying something well defined, which is most vehicle purchases.
The defining feature is that the agency has already made every decision except who supplies it. That is why the specification carries so much weight: once bids are open there is no room to weigh a better vendor, a shorter lead time or an easier machine to maintain unless the specification asked for them.
Public opening is the part commercial buyers find strange and it is central. Bids are read in the open, prices become public record, and the process is auditable from end to end. That transparency is the reason the method survives despite its rigidity.