Yeah moderately heavy traffic is _great_ for FE (in my experience), but severe traffic kills it. If traffic's thick enough that everyone's going 30-40 on the interstate, I can get great mileage cruising along like that, but when traffic stops... You're saving power while you're stopped, and using EV mode as you creep forward every so often, until the battery is so low the ICE kicks in. I rarely use AC but I don't know if I've ever seen the engine recharge the battery enough to even notice it when it comes on solely for low battery. Only thing I find I can do is try to avoid it happening by starting to wait until there's enough space between me and the next car to use some gas while I accelerate even the pretty small distance and stop using battery for every foot I drive. Lets me continue to avoid using gas to go 0 miles (which pretty well ruins your mileage), by not idling when I'm stopped. That's about the only solution I've found (except my new mode of skipping the heaviest parts of the nearby interstates on my commute lately--and getting low-mid 40s since I started going cross-country instead!).