A car accelerates uphill does its kinetic energy increase or decrease?
Kinetic energy of the body always depends on the velocity of the body. So kinetic energy of the car can increase even if it goes up hill, as you are saying it can get that energy from other sources.
No it is possible to have external energy put into a system which increases its PE whilst keeping the same KE. For example, a car moving up a hill at a constant speed - the energy from the engine goes into increasing its its PE whilst the KE will remain unchanged.
It is also possible for the external energy to go into increasing both the KE and PE, for example in the situation of a car accelerating up a hill.