[euromodder]

We can go a lot further, definitely !

Jet's take Piwoslaw's car and its 1.6L HDi PSA diesel: 43 mpg - 5.5 L/100km in his 2005 Peugeot 307SW.

The same engine in my 300lbs heavier 2005 Volvo V50: 47mpg - 5.0 L/100km.
In the 2009 (?) V50 Drive : 4.5 L/100km - 53 mpg
In the 2010/11 V50 Drive Start/Stop : 3.9 L/100km - 60 mpg.

In mpg, that's a 39.5% increase, or in L/100km a 29% decrease.
For the same engine in very similar cars, over only 5 years.