Awful is the opposite of Excellent. Excellent is the opposite of Horrible. Killing can cause/lead to Horrible. 
Auto is etymologically related to Automatic. Auto is related to Car. 
Awful <--Antonym--> Excellent <--Antonym--> Horrible <--Causes-- Killing 
Automatic <--EtymologicallyRelatedTo-- Auto <--RelatedTo--> Car 