Another thread about this topic which never really goes anywhere. What I'm finding is a normal commute to and from work of about 10 mile the engine hasn't warmed up fully so I'm only getting about 42/43mpg. The other day while on a run out on the motorway I reset the @2 mpg and it stuck at over 55mpg! It stayed there but is gradually dropping back down due to the commute. My point is this. If the engine was to warm to optimum efficiency sooner you WILL see a difference! I used to remember my dad putting some cardboard on the grille of his '84 Volvo estate to do just that. Surely something can be done here ???