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Only thing you can do to improve an auto enhanced score is have more positive auto loan trade line history. You should focus on improving your credit report entirely. I suggest you visit the "Rebuilding your credit" section on these forums. Read the sticky that goes something like "What steps do I take? DV? PFD". Lurk those forums, and read a few threads. Also dont forget to pull your credit report on annualcreditreport.com as you will need it. Hope this helps.
Here is a link to the sticky: http://ficoforums.myfico.com/t5/Rebuilding-Your-Credit/What-Steps-Do-I-Take-Do-I-DV-PFD/td-p/337142
Also consider financing with smaller CUs/leanders that don't pull auto enhanced. Like DCU for example. When you apply by yourself to DCU, they pull regular FICO!