2017 Renegade Trail hawk - We like it for around town but we’re disappointed with long road trip mileage. So we are on our second trek from Tulsa to SoCal and 1/2 way back we hit 15,000 miles and the Jeep starts running better (holds power uphill better, peppier at take off) and average fuel mileage jumps by 5 mpg. Is this typical engine or trans break in or did it cough up a hairball? What is your experience?
If there's is any break-in, which new cars now a days don't typically need, it will be the first few hundred miles, assuming the engine sees all rpm and load ranges. When you say 2nd trek, do you mean 2nd time around for the trip, or 2nd leg of the 1st trip? Fuel quality changes? How about elevation? So many different variables.