I have always had gasoline cars, for which it appears (based on advice from other motorists and from fuel consumption meter), that it is advisable in general to run them between 1500-2000rpm.
Going above 2100-2200 for longer periods seems to increase fuel consumption significantly regardless of speed/transmission and rpm of around 1500-1800 seems to be what should I aim at.
Now I have bought a 2005 Honda CR-V 2.2 CTDi turbodiesel, and I have been told by a CR-V enthusiast, that I should in general aim to stay around 2000-2500rpms, for best fuel consumption and for longer engine life, as staying in this range would be better for dealing with exhaust gas recirculation and soot filters.
Is it true in general, or could it be true for this specific engine/car? Also, is my initial presumption about gasoline engines correct?