Well at least you're considering another German car, the Jetta should be a fine choice. But if you're going to autocross the car once in a while, just remember that the jetta is a front wheel drive car. Have you considered a 1993 (latest generation) RX-7 twin-turbo? I know how everyone says they are not that reliable, but if you keep in in good condition, it should run. I think you can find a RX-7 for around 12K. These cars are so fast! 0-60 in 4.9 stock! And there are many options if you want to tune the car because its eaisier to mod a twin-turbo than a naturally aspirated engine.