i am using the addforce method but with the force mode on change velocity (with some test this one was the closest to what i wanned for char. movment) the thing is i apply the force on the forward direction of the transformer without acounting for the angle of the ground , so it applyes the force needed to reach the desired speed but the slope still interfiers since the force appears at an angle towerds it.
PS.: unity docs mention that direct change to the velocity field is not adviseble and should be avoided.