The delivery system was very 'inefficient'.
The engine uses fuel 'inefficiently'.
an 'inefficient' use of fuel
(..) the right stuff! The toilet cleaners! They said we couldn't do it! They said outsourcing our toilet cleaning would be inefficient! Derk, Banhead and Doodles proved them wrong! Toilets! That's right Doodles! Where are you going? (..)2006 TvShow: The IT Crowd Title: Aunt Irma Visits Season: 1 Episode 6