Ya I dont believe the 180 mph average either, especially since no stock Camaro has ever been capable of exceeding 165 mph, not to mention the fact that to average a high speed like that, you have to have been traveling much of the time at a much greater speed.
Also, BMW M5s are governed at 155 for whoever said they went faster than that in one. Car and Driver just had a great article about why all BMWs have speedometers that read much higher than the car is actually going. I have read an estimate that said that a current M5 should be able to reach around 180 with governor removed though.
I also dont believe most of the stories about muscle cars from the '60s going much beyond 140 mph. There are 3 key components to going really fast as in top speed. (1) gearing, (2) horsepower, (3) and most importantly, aerodynamics. American muscle cars from the '60s were extremely powerful, even considering that the horsepower figures given for them by the manufacturers were gross horsepower, not the currently used net horsepower. However, these cars were designed to accelerate fast, being more intended for drag racing than for top speed contests. The aerodynamics for these cars prevent them from going much beyond 140 in most cases without lots of tuning. Most cars from the '60s and early '70s were geared for quarter mile optimization and not for top end speed. I saw an article on a Dodge Challenger once that had the 426 hemi in it, rated at 425 hp. This car was a stripped down one intended for drag racing, and the hemi was one of the few engines that was underrated in hp by its manufacturer, due to insurance concerns. Even given modern net hp ratings, the hemi would probably show around 400 hp. This car, despite having all this horsepower and a monster amount of torque as well, topped out at around 118 mph. Why? because it had a 4.10 rear end and a low geared 4 speed tranny. This car was extremely fast in a drag race though, 1/4 mile was in 12.9-13.1 sec range with trap speed of around 110 mph if I remember correctly. Even if this car had much taller gearing though, aerodynamics would probably limit it to around 145 mph. The fastest car from the '60s, bone stock was reputedly the Shelby Cobra with 427 (if this car could even come close to being considered stock) lol. Some of the more reliable road tests, indicate that this car could top 150 mph under certain circumstances. Some Dodge Superbirds, with more attention paid to aerodynamics, and souped up quite a bit, were able to top 160. And the famed Andy Granatelli, was able to hit 190mph in the flying mile, with some heavily modified cars from the '60s. These stories about stock Chevelles, GTOs, and other muscle cars from the '60s going 170 mph are largely bogus though.
Just remember, the max number on the speedometer has NOTHING to do with the potential of your car. I have seen Corvettes with 85 mph on speedometer and other much slower cars with 160 mph. I cant tell you how many times people have told me, "my car can probably do 150, thats what the speedometer has on it anyhow". Also, speedometers are quite inaccurate, often lying by as much as 20 mph or more at high speeds. Motor trend used to show what some of the supercars they tested indicated, and then what they were actually doing as verified by a 5th wheel speed measuring device. It was quite a revelation.
