wheel barring
you need to get your front end aligned
Check the front wheel ball joints. Even more likely is the wheels/tires are out of balance.
warped rotors(brakes)...most likely front ones
Inspect your drive belts for wear or looseness.
I have a 2001 mercury sable LS premium DOHC 24V engine and usually around 70 I'm at 2500-3000 RPM's
50 knots = 57.5 mph
109.09 mph
62.14 mph
He was arrested in 1955 for going 35 mph in a 25 mph zone.
100 kph is going 62.14 mph.
if you are going 50 mph 153.5 hours if you are going 60 mph 127.9 hours if you are going 70 mph 109.6 hours
2002 alero no power over 45 mph