Over the last three days I used the Volt to go fishing, no luck, but gave it a good try. Looks like the recall did increase mpg's on the gas engine. I averaged 54.14 mpg, used 3.45 gallons, gas miles, 186.8. Also electric miles 203.7. This is with winter temps in 40-57 degrees max. Summer temps, with summer formulated gas would have probably been in the high 50's mpg. I am a conservative driver but drive the speed limit. Mainly mixed highway driving via Highway 101, on the coast...
Looking at the stats, voltstats.net, during the summer we averaged mid to high 40's mpg.