Never before have you had so many choices of great cars for under the $30,000 mark. Choosing the right one really depends on what is important to you.
For value and longevity, Honda serves up almost one of each model for under the line. The Civic starts under $20K, and finishes way before the $30K line. The Accord Starts around $25K, and can go way over, but you can get a very nicely equipped car and stay well under the line. Subaru has always been known throughout the world as a workhorse, and has only really caught on here in America in the last decade or so. Both the Legacy and Impreza start around $25K and just like the Accord, can stretch above the limit, but can certainly be had for under the $30K mark. And all come with Subaru's legendary 4-Wheel Drive system. Which, is AMAZING.
If you are after safety and sporty, look no further than Volkswagen! Starting with the Rabbit at a starting price of under $18K and running up to a baseline Passat at $28K the entire model line is a combination of expensive luxury mixed with a high level of performance wrapped up in a seriously tough and safe package.
Under the $30,000 limit you can still get into a high level of luxury also. The Volvo S40 starts just a hair under, and is setting new standards for this category, and is giving the Acura TSX a good run for it's money. The Acura used to be alone in this category of "affordable luxury".
Should you be looking for a car that is fun, safe, reliable, attractive, fun, has amazing interior size, is FUN, great gas milage, is a great experience, and is really really FUN to drive - head straight to your local MINI Cooper dealer. Ringing in under the $20K mark and extending way past for the tippy top of the line John Cooper Works MINI Cooper S, the baseline MINI Cooper comes with the most airbags, ABS, traction control, power everything than any other car in it's class.....