(I’m in the US where the speed limit on most highways is usually 65 or 70 mph)
The speedometer on my car tops out at 140mph. Aside from getaway drivers, who would ever need to drive that fast? Is there something about engine design that makes it too hard to have a max speed of 90/100 without affecting the overall function?
In: Engineering
It has to do with gear ratios. You would use the highest gear at highway speeds to keep the engine rpm’s low for fuel efficiency.
You would not want your engine revving at 6,000 rpm for the car to go 75 mph. This is a relatively normal highway speed. They make it closer to 2000 rpm by adding a larger gear. This way, the engine runs at a more efficient point of the power/torque curve when you are at the expected speeds, but the car could go faster than it is probably safe to operate at rpm’s higher than they would want the engine running at over a length of time.
As others pointed out, the numbers on the speedometer mean nothing; I have a 5.0 Mustang where the speedo goes only to 85 mph. I have had it faster, the needle just keeps going
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