Just how bad is the A318?
Do the fuel-burn and increased landing charges completely wipe out any potential gains from not having to get things like type ratings sorted out?
In a word, yes.
Empirical evidence from the world fleet:
Number of airlines operating:
A321: 66 airlines, 522 aircraft
A320: 173 airlines, 2025 aircraft
A319: 89 airlines, 1118 aircraft
A318... 6 airlines, 57 aircraft (7 and 59 if you count BA's 2 impending LR aircraft)
The A318 is the second lowest-selling Airbus (after the A340-500). Lots of airline finance departments' Excel sheets giving similar answers...