Mine will get up to about halfway if I drive a lot of short trips and then it regens. I just go drive around until it's done. If I'm local I use the gear limiter to keep It around 1500 rpm. It seems more frequent in the winter, im guessing due to colder exhaust temps and a lot of warm up time. If I'm on the highway it'll actually go down if i drive long enough, towing or not. If I tow it never goes up. I did about 325 miles today. I started at about 30% full and it was 0 when I got home. No trailer. Mostly thruway driving around 75mph.