14. 1969/70 Ford Mustang Boss 429: $550,000
The mythical Mustang Boss 429 is a proper muscle car legend. Ford conceived it in 1969 as a pure racing engine they intended to use in the NASCAR championships. The Boss 429 featured a different engine architecture than the rest of the Ford big blocks, making the Boss 429 much wider. It also had semi-Hemi combustion chambers that helped achieve higher revs, resulting in a better flow inside the head. Ultimately, it produced more power and torque.
With factory ratings of 375 HP, this unit produced over 500 HP, but it created much more in race trim. Ford decided to put this engine into the Mustang, offering a limited production Boss 429. However, NASCAR decided not to homologate it since they only accepted intermediate and full-size cars, and the Mustang was a pony car. So, Ford homologated the Torino Talladega as the body and the Boss 429 as the engine.
The company participated in the 1969 season with the Torino and Mercury Cyclone, both with the Boss 429 engine. Those cars proved successful, winning 30 out of 54 races that year. The secret was the engine. They designed the Boss 429 to run at high RPMs for long periods of time to achieve peak power, high in the RPM range. That is why the Mustang Boss 429 never fulfilled its street racing potential.
Available only in 1969 and 1970 as an engine option on the Mustang Sportsroof, they only produced 1,300 Boss 429s. That limited availability is what has made the Boss 429 a highly-sought-after model in present years. An unbelievably well-preserved Mustang Boss 429 sold for a whopping $550,000 in 2013. It was in its original condition with only approximately 1,000 miles on the clock. This time machine condition justified the enormous price, but many restored Boss 429s Mustangs also command high prices.