Has anyone had their car's engine software remapped to improve fuel efficiency rather than gain more power ?
Rica in the Netherlands claim up to 15% increases in FE for the 1.6D engine in my car with an E-power upgrade !
RICA Engineering - Performance and Economy Tuning for Volvo, BMW, Audi, VW, Mercedes and most other makes and models
The FE numbers shown are not the official European testcycle ratings, but rather the results of their own (outsourced) testing.
Considering it's actually less (!) expensive as having my rear windows professionaly tinted, I'm tempted to give it a try.