New Truck - X15 Advice

[Lonestar10]

hopefully with being informed how to drive a cummins from here youll do better than my dispatchers brother

2019 - 389 - X15 Perf Series - 565/2050 - 3.36 rears - 18sp - pulling flatbed.

hes struggling to get 5MPG vs the truck he traded which was a 379 3406B with 3.55s i dont know trans prob 13-18 and probably 500+HP that truck netted him 6.5MPG all day long with 1.3Mil on the clock without ever being opened up. now hes getting 5 so not only 3000+ truck payment but 1.5MPG more in fuel and DEF.

Its hard being the guy with 6MO O/O offering advice to guys that have driven for years for themselves. my dad just says "believe everything you see on the internet" when i tell him that cummins like the higher RPMs he says his just sounds like it wants to explode above 1500 (CM870). and offering advice to the other guys who just bought new Perf and Effic Series. no one wants to hear it. although the guy with the 389 did nonchalantly ask if my laptop can "fix" his truck but didnt ask about it further. i did say it can but i dont have the information for his engine but knew people who did.