Do not buy the Sonata Hybrid for its gas mileage. The vehicle will achieve the advertised highway mileage but the city mileage performance is erratic and the idea that it can achieve 35mpg in city driving is absurd. All the dealership can do is plug in their computer and look for error codes. When no error codes show up they tell you the car is performing as designed even if the mpg is only 26. Also do not waste your time contacting Hyundai Motors America customer service. The only response you receive from them is a referral back to the dealership and a list of the reasons that you may be at fault for the low mpg because of poor driving habits. They are a waste of their company's resources.
Do not sell any more of the Sonata Hybrids until the car can meet the advertised city mpg consistently. Hyundai was improving their reputation for quality vehicles until the Hybrid came along. I have a 2011 gas version of the Sonata and it meets the advertised mpg ratings both city and highway. The 2011 Sonata Hybrid simply fails. All the complaints you read from others in this forum about hesitation when starting up are also true.