The Prius seems to be doing ok and that isn't really saving anyone any money. They have been making it for over 10 years now so someone must have been buying them. Some Prius owners (in city driving) are claiming they are only getting around 35mpg. You can buy a car that gets around 30mpg for about $10,000 less.
Well, you always have the smug factor, but some people want the extra weight(IE features) and accelleration that a hybrid can offer while still getting good gas mileage.
The price difference between a Honda Civic and the hybrid equivalent, for example, is about $2-3k.
I'm going to go with an almost exclusive city driver. Let's say our test subject is an independent inner city taxi driver, salesman or something. Lotsa mileage, all city.
NonHybrid: 25. Hybrid: 40. Gas: $5/gallon. Hybrid: $3k extra
Cost per mile: $.20 vs $.13
Break even point: 40k miles. Less than 3 years for the 'Average' driver who goes 15k miles a year. Doable. If we figure gas is going to float at $4 for the next few years, it'd be 50k miles, a little over 3 years.
It doesn't much sense for the highway driver - over seven years with gas at $5. Of course, if we figure he drives twice as many miles, that'd drop it to 3.6 years.
On the Toyota side - the Prius mentioned is cheaper than the civic hybrid and gets better gas mileage, and has more passanger volume and cargo room. The Matrix seems to be a pretty close competitor - but is 6.5k cheaper. Still, the Prius gets better city mileage - it's break even point would be 4.5 years at 68k miles.
Disclaimer: I got my information off of Honda and Toyota's sites using published EPA mileage. I make no claim as to the suitability of any given vehicle for any given task, or the comparability between them. As the EPA says, mileage varies depending on driving patterns.