Modifying your car can be a great hobby and help make your more efficient or desirable. It can also ruin a classic car and deplete it of all its value, especially if you mess with a car that is a factory-perfect rare gem like a Plymouth Road Runner Superbird, an 1987 Buick GNX, or the original Hemi powered muscle cars of the 1970s.
Although it is a challenge, several cars on the market are worth incomprehensible amounts of money and are pristine representations of engineering, that is if they can be found in factory condition. If you are lucky enough to find any of these classic sports car gems in their factory-delivered conditions, do not, for the love of all that is good about cars, modify them.
10 1970 Plymouth Road Runner
Road Runners were kings of the Golden Age of Muscle Cars, especially the 1970 models like the Superbird. They came with either a 3-speed automatic or 4-speed manual transmission and a V8 engine capable of hitting over 300 horsepower.
Road Runners in their best condition can easily fetch over $100,000 at any car auction, and one particular rarity is the Road Runner Convertible, particularly the Road Runner Convertible with the 4-speed manual transmission. In any case, modifications to this car would be a disaster for its auction value.
9 1987 Buick GNX
A turbocharged Buick? That’s right. The 1987 Buick GNX has a marvel of an engine that can keep up with its fair share of modern sports cars and they should be kept up to factory specs, but not modified. Why?
Because it is a turbocharged, intercooled V6 with up to 300 horsepower. Oh, that and the fact that less than 550 of these cars were ever made. Although typically sold for less than $60,000, some lucky sellers have gotten $200,000 for theirs.
8 1970 Pontiac GTO
Like the Plymouth Road Runner, the 1970 Pontiac GTO dominated the American muscle car craze. It had a naturally aspirated V8 engine capable of more than 360 hp. The four-barrel carburetor is also something to admire.
Although later versions of the GTO would ultimately flop, the 1970 release is the envy of many collectors. They can easily fetch over $50,000.
7 1965 Ford Mustang
The first generations of the Ford Mustang forever set a new standard for sports and muscle cars. Each iteration of the first generation of mustangs, (the 1964.5, the 1965, and the 1966) each went through a series of changes. But the 1965 was the first of the Mustangs to use alternators instead of generators, a new technological feat for the time.
Over 500,000 of the 1965 Mustang were produced, but they still retain a lot of value and can sell for an exponential price. Some owners are asking for as much as $70,000, especially those selling convertible trims.
6 1969 Dodge Charger Daytona
There is so much to love about this classic and plenty of reasons why you should avoid mods at all costs. Search long enough, and you will find this car with either a 426 Cubic Inch Hemi or a 440 Cubic Inch Magnum V8 which can easily achieve 400 horsepower.
Only 505 units ever saw the light of day, making this one exceptionally rare sports car. It has sold for upwards of $500,000! Do not, we repeat, do not modify this car!
5 1970 Plymouth Barracuda
Another gem from the golden era of muscle cars, the 1970 Plymouth Barracuda was the first iteration to break away from the Plymouth Valiant, which had served as the chassis for this car up until this point.
A variety of engines came option with the models built between 1970 and 1971, and they ranged from a standard slant 6 to a meaty 440 cubic inch V8. A mint condition Cuda can also come with a hefty price tag, with some sellers demanding over $500,000 for this car as well.
4 1969-1970 Ford Mustang Boss 429
Ford’s 429 Cubic Inch V8 engine, its four-barrel carburetor, and the 4-speed manual transmission are just some of the admirable traits in this rarity, and they also drive its 350+ horsepower.
According to Hagerty, the average auction price for the Boss 429 is over $200,000. Less than 1,400 units were ever made, making it one of the rarest Mustangs Ford has ever produced.
3 1967 Shelby GT 500
Shelby’s are amazing, period. Whether it's the Shelby Cobra, the Shelby GT 500, or any iteration, these are some of the best sports cars ever to see the light of day, and they should never be tampered with.
The 1967 GT 500 is a gem thanks to its 428 cubic inch water-cooled V8 engine with over 350 horses pulling it. They are easily worth $200,000, at least.
2 1970 Dodge Challenger Hemi
The 1970 Dodge Challenger Hemi, especially the RT convertible, is very rare. Of the RT convertible, only 149 were ever made, making them some of the rarest sports cars in the world.
They came with 426 cubic inch V8 engines and were capable of 425 hp. Challenger RT Convertibles have been known to sell for well over $1 million. Think that’s a lot of money? Well, read the next entry…
1 1967 Corvette L88
Classic Corvettes can be hard to come by, so be sure yours is well taken care of. Some even call the L88 the “Holy Grail” of Corvettes and with good cause, especially thanks to their 427 cubic inch capable of 430 hp.
One lucky seller was able to unload their L88 for a whopping $4 million! Now do you believe us when we say do not modify these cars?