6. Pontiac GTO
The first year for the modern GTO was 2004 when the car met universal praise from car buyers and the automotive press. The design wasn’t exactly new or aggressive, but the GTO had a muscle car style and street presence. Under the hood was an LS1 5.7-liter V8 with 350 HP giving it enough performance to be one of the hottest American cars for the 2004 model year. The 2005 model year saw the introduction of the 400 HP 6.2-liter engine and even better performance numbers with 0 to 60 mph time of just 4.6 seconds. However, sales started to decline to 11,000, and for 2006, the final model year, Ford only sold 14,000 the GTOs.

So what was the problem with the 2004 to 2006 GTO? The car was just fine, but it failed to excite car customers like the original GTO did. Simply, the design was restrained and not particularly aggressive. Although the car was fast and performance was convincing, as an overall package the new GTO wasn’t as appealing to new customers. This was the main reason for its early demise and relative market failure. However, most people still feel this car is one of the best modern muscle cars ever.