4: Cadillac CTS-V
When Cadillac introduced the CTS-V, it was the first modern sedan the brand ever had before it was released. The stying and the design were counter culture to everything that Cadillac had offered before. The performance from the stock model was promising. When coupled with the manual transmission, the CTS and CTS-V where surprisingly fun to drive (via Motor Trend).
First generation CTS-V models are still fairly reasonable when it comes to the pricing and these cars are easy to come by. You can find one that has been well maintained and still offers a lot of life left for the price. There are a number of performance sedans from this era, but the CTS-V should be at the top of your list.