I was/am a 9000k a year driver and love my Prius. I am finding that I am driving more without the need to "worry" about the cost of a fill-up. My fiancé a couple weeks ago decided for the heck of it to take a drive to Berryville Va for the afternoon. At 50+mpg we are looking forward to day trips to the Delware shore on our mid- week days off. We are no longer thinking that we can't just go some place because of the cost for gas. And we have extra money to enjoy ourselves in the process. From what I read before buying a Prius, once a week use is good for the Prius. For our plans for a two week honeymoon next year, we have a couple friends that we will have drive us to and from the airport in my Prius. They get to experience Prii Love and get a couple of dinners out of it - and the Prius gets some use.
The new way of cooling the transaxle also improved warming it up efficiently (per SAE 2012-01-0623). GCC has more detailed information about the changes/improvements. Majority of the short trip improvements came from the engine and exhaust side. The following is from SAE 2012-01-1017. LA#4 is known as "city cycle" or UDDS -- see the graph of it.