The 2012 Kia Soul and Forte Koup might be polar opposites, but they share one thing in common. If you're guessing that it's the fact that they're both available for a test drive at Central Kia of Lewisville, you're close, but not there yet. Both new Kia models were recently featured on MSN Autos' "10 Great Cars for Less Than $20,000" list, adding yet another milestone to the fastest growing…