yeah the southern california freeways are pretty flat. but there are just so many cars that traffic slows to a crawl. the gas engine had to keep turning on to recharge the battery. hence the huge difference in max mpg and min mpg int my pic. but some days its like this:
There are spots on my drive home in the evenings where traffic crawls long enough to give me one or two 99.9 bars while the battery is completely drained and then one less-than-25 bar. Like your picture, I can have two of those during a single drive. Rather annoying. The only thing that keeps me from getting too upset with the low bars is the thought that the tank average is exactly that: an average. You can't let a single bar freak you out.