The problem is typically related to tire balance, but it can also be a bent wheel. Also make sure the suspension and steering linkage is tight.
Your first step should be to have the tires balanced. Go to a tire store that you trust. Stay away from the big box stores and try to focus on a local shop that has a good reputation.
About 10 seconds.
There is no direct conversion from horsepower to miles per hour. Horsepower is a unit of energy equal to about 750 watts. Miles per hour is a rate. A small motorcycle engine of 6 HP might reach a speed of 50 MPH. A 6 HP snow blower might reach 1 MPH. A 2,500 HP military tank might reach 40 MPH.
It depends on the rate of speed the car is travelling. For example, if a car is going 60 mph, then it will take 6 minutes to reach 6 miles.
6 hours and 1.83 minutes
81 minutes
.....................................................you wot?
If your 1999 4 cyl Mitsubishi Eclipse shakes when you reach 70 mph, you may need to replace your tires. Edit: I recently replaced my four tires so I don't think it would be the tires though.
Warped rotors
allignment
your tires may need to be balanced
Normally this is a tire out of balance. Have your tires rotated and balanced.
If you are speaking of the automatic transmission, no. The 1997 geo metro has a 3 speed automatic. At approximately 35 mph it will shift from 2nd to 3rd gear. This means that it will run at 3500 rpm when traveling at 55 mph. Most cars with overdrive will shift to the 4th gear (overdrive) at this point. A geo metro, which only has 3 gears, does not.
The 2007 Yamaha R1 takes approximately 4 seconds to reach 100 mph.
Tires/wheels out of balance?
Tire out of balance or bent wheel.
check and replace tires and tie rod ends as neccassary
inner tie rods bad at rack and pinion