Problem with Fixed Timestep

Hi, Im making a project, its a little heavy on physics, its just a car going in the right direction, it have some "steps" it has to follow, all this in 2d with a wheel joint. by "spteps" i mean it has to reach certain velocity as the frames go,

but its impossible to have a consistent result with the fixed timestep and maximum allowed time with the default vaules, but... if i change the values both to 0.01... it works PERFECT... but one problem.. now the car seems SLOW, the gravity is al messed up, it is very very consistent, and that was the point but it has a very strange feeling of slowliness, is there something i can do to make it seem normal?