keep in mind that when buying a new car you should always get one with stability control and side airbags. its a safety thing.
VW- go for the new VW Jetta TDI. the gas Jetta and Rabbit are also a really great choices. if you are willing to spend a little more, get a Tiguan, GTI, or Passat. all VW's (excl. VW Touareg2 V10 TDI) have available (or std.) six speed automatic transmissions which really help performance AND fuel economy.
Toyota- they have been having some real problems lately, especially with their newer models like the Camry and Tundra. until they fix these things, i wouldnt go near one. plus, the newer models have cheapo interiors.
Honda- ok if you fit in them and dont mind the noise. plus, the interior quality really isnt up to par with VW's. therefore, Hondas are not the best cars fo me in either aspect. i dont fit and the noise drives me nuts.
Mazda- the Mazda3 is good on gas and is pretty fun. the new Mazda6 is also pretty nice. if you look at the Tribute, the small SUV like the Ford Escape, wait for the 2009's. they get new engines that are more efficient and six speed-autos opposed to the old four speeds they have as 2008's.
Chevy- the new 2008 Malibu is acctually a very nice car, and you can find "hybrid" versions for pretty cheap. cobalts are lackluster, and Aveo's arent that efficient.
Dodge/Chrystler/Jeep- none of their vehicles would be on my list.
Subaru- dont forget to look at the new Impreza or the Forester. the only setback with them is that they still have 4 speed autos.