COCAK has posted up another guide for the most recent card challenge here.
In addition to the strategy listed in the guide, I found that getting a speed of five and putting the rest into armor is another way to not only beat the challenge, but the badge as well. In fact, I reached almost 9000 points with this method. Anyway the most important thing is to put your upgrades into speed or armor, the other upgrades simply do not cut it. Enjoy your new card. :)