Take solace that you still got better MPGs than your average car that had to keep running and burning gas. If the weather was nice, you have the option of lowering the windows and turning off the car. You don't need to restart just to move a few inches...wait until almost a car length appears. If you want to be comfortable, all you can do is put it in park and take the hit...maybe warm up your A/C so it's not running as often.
Best advice I got on this forum (will have to find the link)... When traffic starts up again after a complete stop (or bumper to bumper crawling), try to wait a bit, then accelerate enough so that acceleration takes place using the gas engine (much more efficient in the big picture than accelerating at the high end of EV). The battery power is then saved for while you are at idle. This advice is especially important when you are on an uphill grade, and this advice has helped me in standstill traffic conditions. The end game is to try to conserve enough "at idle" EV such that the engine doesn't fire up at full stop just to charge the battery. That being said, I agree with qdllc - you're still getting much better mileage than virtually every other car out there!
I agree with "breakfast" above. In these situations accelerate hard every now and then using ICE so that the gas engine is used to directly propel the car. More efficient than only using EV to propel, then the ICE comes on just to recharge the battery, which is inefficient.
It really depends. Some have more stop and very short very slow go in which case firing up the ICE uses more energy than just creeping on battery. Some on the other hand has more creep than stops so P&G works better. And like somebody already said... were over thinking this too much lol.
I have found Eco mode pretty much doubles how long I get in those situations if the ac is on since it changes the ac power consumption. But some use PWR to induce the ICE to kick on sooner when you start creeping forward. I usually try to hit the pedal hard enough to force the ICE on in Eco mode if it is safe to do so like someone else said. And yes, I have overthought this just like the rest of you haha. Traffic James and idling is the only time is use Eco mode.