There may be something wrong with the accelerator. It might be time to get the vehicle checked out to ensure nothing is wrong.
Perhaps: Fuel filter Air filter catalytic converter
8
8
2 secs
My guess would be wheel balance.
accelerate going downhill should make it go near 120mph
I think we need to know the distance the police car took to pass the speeding car to answer that one. The police car traveling at 75 mph would eventually pass the speeding car traveling at 74 mph.
It would be a transmission issue, not up shifting. If the engine is in "limp mode" it will not accelerate over a set mph.
a = (vf - v0)/Δt 10 mph/s = (45 mph - 20 mph)/Δt Δt = 2.5 s
I work that out as 4.87 seconds.
I would change the fuel filter first; I suspect it could be a fuel delivery problem ; but make sure air filter is clean also.
There is no such thing as 20 mph acceleration. 20 mph is a velocity. Acceleration is expressed as velocity per unit time e.g. mph per second or mph per minute etc.