There is no savings from a hybrid. The purchase price is known but the O&M costs are currently unknown to the market. The only benefit is that you get to use the HOV lanes as a single driver. That will change as soon as more hybrids are bought. If you want to really save money on fuel ride a motorcycle. You actually save money and will always get to use the HOV lanes.
Aren't tires for motorcycles expensive {$200 - $400 for 2} and they don't last that many miles - 10K or so {this is for the faster bikes, maybe regular bikes last longer}? I would think that would eat into any fuel savings.
I get 36 mpg overall in my 04 Toyota Corolla. I am afraid, I would get killed if I bought another motorcycle since I would go too fast on it and a lot of drivers have difficulty seeing you.