why do speedometers go as high as 140 – 160 mph but some average cars can’t go faster than 100 -120?

Question

why do speedometers go as high as 140 – 160 mph but some average cars can’t go faster than 100 -120?

In: Technology

Answer 1

All cars can do 120+ mph, going down an extremely steep hill, with “hurricane force winds” pushing it; even if the car isn’t turned on. There’s multiple alternative methods – being towed/pushed by race cars; being launched by catapult (like the aircraft catapults on an aircraft carrier), various modifications (e.g. getting an after-market turbocharger installed), etc.

The “alternative alternative” is if the car isn’t actually moving at all – e.g. on a device called a dynamometer where the car’s wheels sit on rollers; and the wheels can go faster than normal because there’s no wind resistance to push against when the car isn’t actually moving.

With a lot of engineering, you just shrug your shoulders, take whatever is realistic as a starting point and then say “let’s add 50% (or double it or…) to be safe”. A car that might only do 100 mph on a flat surface using its own power with no assistance and no modifications ends up with a 150 mph speedometer because it might be going downhill and/or might be getting assistance and/or might be modified.

For the same reason, a car that might only do 180 mph on a flat surface using its own power with no assistance and no modifications ends up with a 260 mph speedometer because it might….