Before installing Numenor's recolorable Fiat Punto from Mod The Sims 2, you must remove the original version (which you would have downloaded from the UK Sims 2 site) if you have it. If you skip this step, recolors for the Punto will not show up in your game.

First, check to see if there is a file named
3b603e7a602d4375ac7d426abb341338_0001.package (May have more or fewer 0's)
in your \Downloads\ folder. If so, take it out of the \The Sims 2\ folder. Do not delete it yet!

Once the file is moved, install Numenor's recolorable Fiat Punto and at least one recolor. Run the game. Click the Punto under "Miscellaneous/Cars" and see if the recolor shows up. If it does, congratulations! You can now delete the original Punto file that you moved out of the folder.

If that doesn't work...

...then the file was installed with a different filename, and you'll have to find it with Sims2Pack Clean Installer, available HERE.

The file is listed inside Clean Installer as Name: "Fiat Punto," Type: "Game object." Click either header to sort files accordingly.

If you have already installed Numenor's version while following the instructions above, his file will be easily recognized by its new name: "Fiat Punto (c)Maxis - Colour option by Numenor." Do not disable that one!

Once the original "Fiat Punto" is located, right click the file, and choose either "Disable Package," or "Move Package."

Install Numenor's recolorable Fiat Punto (if you haven't already done so) and run the game. If the recolor shows up, you can "Remove Package" through Clean Installer to delete the original version (if you want to).

For more information, consult Numenor on MTS2.