I once took a 1982 Honda Civic 1800 coupe up to 100mph with three other frat bros in the car and they had no idea we were going that fast. I got 40 mpg in that car most of the time.
Around 20 years ago, I was driving on I-10 between Crestview, and Pensacola, FL. My pickup was an 86 F250. It had dual exhausts and I had replaced the quirky carburetor with a less expensive Edelbrock. I had also had an older model valve timing gear installed to increase HP and mileage.
A Porsche passed me at a high rate of speed. I thought well I can just tail behind him a few hundred yards and he will get the ticket if a cop shows up. This continued for maybe five miles and he apparently got tired of me following him and took off. For some reason I decided to see if I could keep up with him.
The speedometer only went to 85 but I noticed the RPMs eventually got up to 6000. I later did some calculations and I had to have been doing a bit over 140. The pickup was driving extremely smoothly, really better than at normal speeds but I happened to glance at the heat gauge and it was all the way over to hot. I just let the Porsche go.