Actually it is all CGI (and a viral commercial):
http://www.snopes.com/photos/commercials/sportka.asp
http://www.joeytomatoes.com/fordcat.htm
Title: Ford Cat
Type: Viral*
Agency: Ogilvy
Advertiser: Ford
Brand Name: Ford SportKa
Country of Production: UK
Market: Europe
Target: Young males 18-34
Campaign: Evil Twin
Type: Television
Air date: 2004
Length:40 sec
Viral Video Clip
Viral marketing, if leaked without permission, can be like a contagious disease.
Silently transmitted and virtually uncontrollable, it can create unintended distress.
On April 1, an unapproved viral advertisement featuring a Ford Sportka car was leaked
onto the internet and began to be transmitted by email around the world.
This "advertisement" was not approved for release and was not sanctioned by either Ogilvy or our client Ford.
The action in the video clip was totally computer generated, and we would like to
assure you that no animal was harmed in its making.
Ogilvy and Ford of Europe deeply regret that this unapproved and unofficial
video clip was accidentally released and apologize for any offense it has caused.