ES300h owners are getting 35 to 38 MPG in my area, there are a lot of traffic lights and the weather is over 100 degrees during the summer.
If you have the heater on the engine will need to run to supply heat for the interior. If you are interested in higher MPG numbers drive with the heater off for the first 4 miles.
Don’t give up so easily, with some driving adjustments your fuel economy values will be much higher.