The auto=enhanced FICO is heavily weighted with informaion from your past auto accounts. It scores you more strictly on that information, and more lightly on other information than regular FICO scoring models.
Credit card utilization, average age of account, credit card payment history, etc. - these things just don't weigh as heavily in the auto-enhanced model.
So actions you take to optimize your regular scores - cutting utilization, for example, or increasing available credti lines - do not help your auto-enhanced score.
If you have any past issues with auto loans - late payments, reposessions, default balances, collection activity, chargeoffs, etc - your auto-enhanced schore will suffer.
To improve it greatly, you'll need to deal with/eliminate these specific issues. These issues will affect your auto-enhanced score whether you were the primary borrower or the cosigner for the loan with problems.
If you have never had an auto loan on your own before (had a cosigner), your auto-enhanced score will not be optimized. Only way to fix this situation is to have a loan written in your name and reporting on your credit.
If you have never had an auto loan, period, same thing applies - your auto-enhanced score reflects the risk with a first-time buyer. Only way to eliminate that is to have a loan written in your name.
If you have no experience with any sort of installment loan whatsoever - auto, mortgage, personal loan, student loan, whatever - then your auto-enhanced score, which considers installment accounts more heavily than revolving ones, will suffer for this also. In this case, if you can arrange a small ($500) personal secured loan through a credit union, you might be able to add some points to your auto-enhanced FICO once the loan reports, and if it's small you can pay it down quickly so that it doesn't adversely affect your DTI.
Generally speaking, if your auto-enhanced FICO doesn't budge even when you're making strides on your regular scores (congrats on that, by the way), it means you have some negative reporting in your recently passed auto/installment history, or that you have never had any installment experience at all. One is easy to fix, but the other will take a focused effort and possibly some cash (if you have out-standing balances on an old loan).
