Mid 30's is pretty decent. I doubt there is anything wrong with the car.
CR is bitterly criticised here for the low numbers they report on their city loop with Hybrid cars;i.e. 35mpg Prius (2004-2006) and 26 mpg 2006 Civic Hybrid, 16 mpg HH. However if you drive the Hybrids like normal cars,and do pure city driving with lots of short trips, these numbers are about right. Your mid 30's is roughly what you should get if you drive like they did to produce the 26 city and 47 hy that they reported;the average would be 36.5 mpg.
CR drives the cars they test like a "normal","average" driver.They don't coast,they sure as hell don't pulse and glide, they don't get off the gas early.My guess is that they drive fairly hard using either the brake or the gas pedal and rarely having their right foot on the floor. Most people drive in exactly that fashion-gas-brake-gas-brake-never gas-coast-coast-coast.
Hybrid owners are not normal; they don't drive normally or in any way that vaguely approaches average. A new Hybrid owner who drives normally will get CR type numbers. Now if they get bitten by the MPG bug, they will start up an initially steep learning curve,and the MPG will go up. If you adopt those techniques you'll probably add about 5 mpg over the next few months.
The mpg numbers you see in the real life records kept on this forum aren't representative of all Hybrid drivers.They-we-are MPG FANATICS-NUTS! There will always be reporting bias in these types of surveys. The really committed fanatic reports, the casual drivers don't.Look at the bottom 10-20% of the surveys. Those folks are probably close to "normal" drivers.
We have folks who draft at speed to improve mpg.The drafters are probably reformed car-truck-auto fanatics ,so they are probably very adept at doing this,and it is probably reasonably safe for them to do it. Heck, a lot of normal drivers tailgate as closely because they are daydreaming, or angry, or just unaware of stopping distances.
Your numbers are normal. The numbers you see here aren't "normal."If you adopt a few tricks your mpg will improve 3-5 mpg over time.Luck,Charlie