"I'm gathering from this discussion that the hybrid saves gas in city driving, not highway. My only use of my car is on the highway (I walk to work) so what should I buy?"

Though hybrids don't get as dramatic of an increase in mileage on the highway, they do get better mileage. Partially it's because they're designed to be more aerodynamic, but as I understand it it's mostly that they use a smaller, more efficient kind of engine that trades power for gas efficiency.

Apparently something called the "Atkinson cycle" engine has better fuel economy but less power. It doesn't have a problem maintaining speed on the highway, but it's slow at accelerating - which is where the electric motor kicks in and gives your car the acceleration it needs (aka the acceleration you want). So a hybrid is able to use a more fuel efficient engine by compensating for the 10% of the time you're accelerating by using the electric motor. (If you were in the city you'd accelerate more, but since you're also breaking more the battery would recharge more).

So...that's how a hybrid gets somewhat better mileage on the highway than a non-hybrid. Whether it's worth the cost is up to you. What I *would* say is that if you spend all your time on the highway, you're going to get much better mileage from a sedan than an suv because wind resistance is much more important. Just take a look at the mileage figures. :-)