Allmendinger was suspended temporarily by NASCAR on July 7 hours before the race at Daytona when his sample "A" urine test from the weekend before came back positive violating the substance-abuse policy NASCAR has in place.
Car owner, Roger Penske, has named former Indy Car ChampionSam Hornish Jr. driver of the No. 22 for the time being. Hornish has been in NASCAR's Nationwide Series for the past season and a half after a short stint in the Sprint Cup Series.
NASCAR will not release what Allmendinger tested positive for due to its confidentiality agreement but it is widely speculated that something in Allmendingers diet may have caused a chemical reaction forming the substance that is banned by NASCAR,
Now Allmendinger has the choice to take leagal action to fight the test or start NASCAR's Road to Recovery program. The program takes about five months to complete and is full of counseling, treatment, rehabilitation, and further drug testing.
NASCAR has a zero-tolerance policy when dealing with drug testing and actively has random samples taken from drivers. Jeremy Mayfield was the first driver ever to be suspended indefinitely by NASCAR for violating it's drug policy.