The reason an automatic car uses more gas than a manual transmission car is that the manual transmission weighs way more than the automatic transmission does.
Another way to save on weight is to buy a car without air conditioning. If you live in a Northerly location, this may not be much of a sacrafice.
Driving a stick can actually be more fun and give you better handling on curves. The only drawback is that the acceleration is slightly slower than automatic, so you may get people on your tail when starting out of a stop light. Also, on a hill, you tend to roll back more when you start from a stopped position. People with automatic cars forget about this possibility and often pull up very close to you on a hill light and then are a bit freaked out when you come sliding back towards them when you pull out!
Whether you go with a manual car, a small compact car or a hybrid, buying a gas saver car is the thing to do!