Left for Tennessee last Sunday with our 2011 Yukon Hybrid (~80k miles) and ~5600 lb travel trailer for a maiden long trip voyage (have not scaled it, weight is estimated). Overall truck did great in the hills of TN and KY. Stopped in Brooklyn, Michigan on the way back for camping at state park for Nascar race, will be home finally on Monday. Should have some pictures posted up later next week. Here’s a few observations so far...overall impressed:

Pros:
- 2-mode in hills was awesome...cruising 55-60 mph it would generally hit an RPM, get up to cruise speed then slow engine speed down to maintain. Very smooth torque and acceleration.
- Dynamic braking downhill was great for not going too fast due to momentum. Periodically would go into M4 or M3 mode but never felt like speed was increasing and was very predictable.
- Stop and go traffic near Cinci, went into electric mode and stayed there (mostly downhill)
- Braking and acceleration overall was satisfactory. - 9.2 mpg on way down, 9.9 on way back to MI (did some semi drafting at 65mph in Ohio).
- Even with 92°F weather yesterday, trans stayed below 175° the entire trip.
- Over 1200 mile trip, no noticeable oil consumption.

Cons:
- Engine cooling seems under capacity...through hills it never got under 215°F and consistently was between 220 and 230°. When ambient temps went back below 75° last night it stayed about 210° through Ohio.
- On the way down when temp was up to 220° we stopped for gas and temp gauge was pegged after starting truck back up. After engine ran for a few seconds the coolant was back down to 210°, so my guess is it heat soaked when shut off at gas station. Lesson learned to let it idle for a while before shutting down when warm! Auto stop is definitely not prevented when temps are above 210.
- Trailer sway was horrible with wind even with my anti sway fully cranked down. The hitch receiver has a lot of lash so I’m thinking that contributed. I’m thinking the auto leveling shocks in the back may be wearing out as well.
- US27 is NOT a highway I’d recommend while towing for traveling north from Knoxville area. Made it through OK, but a few turns were hairy!

Anyone else have some good hybrid trailering stories to tell?