40mpg in stop and go traffic? This is where the hybrid shines. The engine may never turn on and it is all battery if the speed is less than 30mph. No jack rabbit starts accelerate discharge the battery coast and break to a stop charge the battery.
In certain stop go situations they can be more efficient while sufficient charge is in the battery. In very cold weather they loose 2/3 of their range. At highway speeds there is no comparison, and on price without government subsidies there is no comparison.