I bought the bike with 50miles. I'm not sure how it was broken in? It's my opinion that after 50miles it would be "broken in". It now has 430mi on it...and got exactly 38mpg this next fuel stop.
My 2018 roadster has SE slipons ,SE round air filter and pro street tuner with 2 tune runs ,I am about 210 I get about 45mpg .
Mixed city hwy not bustin but staying ahead of most traffic.
The twist of the throttle is directly proportional to your fuel mileage. My mileage was affected on my 2013 Road Glide while I was listening to my new slip-ons, after I got used to them the mileage went back up.
2018 forty eight, totally stock with 300 miles. I get around 48mpg.
I weigh 175lb. Also, since this engine is breaking in, it was light riding with no WOT and generally easing on the throttle. Keeping the bike below 3300 rpm.
When I ride north into Oregon on 101, 51 mpg, it is fairly flat, rarely get above 60 mph.
Southbound toward Eureka is hills, lots of curves, multiple stretches to go flat out, mpg drops to 45. Mostly stock 2012 XL883l, a not so low Super Low.