It's best to do it in Post, but...

-One quick and dirty way to do this in MAYA would be to mess with your cam's shutter speed, using a 2D or 3D MBlur on your object(s).

-TWO quick and dirty ways to do it in POST would be:

WAY 1:

1. Render the frames of your Maya scene that you want to go really fast at a frame-rate of 45 frames per second.

2. Using your compositors "interpolation" feature, stretch the length of your frames in a NEGATIVE direction, thus, making them appear to go faster. (In After Effects, this feature is called "Time Strech"). EXAMPLE setting: (-50%)

WAY 2:

1. Render the frames of your Maya scene that you want to go really fast at a frame-rate of 15 frames per second.
DON'T use any Motion Blur.

2. Bring those frames into your compositor, and again, using your compositors "interpolation" feature, stretch the length of your frames in a NEGATIVE direction, thus, making them appear to go faster. (In After Effects, this feature is called "Time Strech").
EXAMPLE setting: (-50%)

3. Use your compositor's bluring, or frame blending features to add the drama of speed, that way you can control the detail of your shot a little bit more

MY prefered way to do this is below

1. Render your maya scene at 30 frames per second.

2. Bring those rendered frames into your compositor, and adjust your comp's output frame rate to a higher frame rate than your rendered frames.
EXAMPLE:
-Your Maya frames are rendered at 30-45 frames per second.
-Your Compositors frame rate output set at 60+ frames per second.

3. Use your compositor's bluring, or frame blending features to add the drama of speed, that way you can control the detail of your shot a little bit more


Hope this helped