What was the last year that a diesel engine got good mileage

[Canadiandiesel]

The custom tune is probably efi live, where the tuner can adjust each injector pulse width, pressures, timing more or less everything programmable on the engine however 06 and up can get this try are working on the 03-05 right now. Costs vary the basic program ranges from 300-500, not including the v2 and programmer, however it's worth it,

And btw I have never seen a ford or Chevy come close to the fuel economy of a cummins isb, one issue is those extra two cylinders another is its a v8 design

[sunsetrider2011]

dodge Rams 2500 and 3500 series ,2000,2001,2002 all were good milieagers, my 02 is anywhere from 1000 to 1200 on a tank empty, 750 to 800 loaded with a trailer. I dont have any of them chipped and are true work horses,, anything before the rack fuel system in my opinion were better on fuel and power.

[bluetick hounder]

I am going to sell my 92 dodge 12 valve. Gets 26 mpg all day long, still in pretty good shape, new tires and lift pump. Pm if interested

[7 REM MAG]

id be careful running that much power on a "tune" without doing air(exhaust/intake). that can result in running real high egt's.