We can only guess as to what an auto-enhanced FICO would be based on this or that event. I don't specifically know what your Harley note is doing. If scored as an auto loan (should be listed as such on your FICO report), I'd argue that the recentness of the loan is a small drain on your FICO, but that's rapidly departing. You won't know what your score is until you apply, and that's assuming they used an auto-enhanced and also assuming they'd pull the same report you pulled to get the 601.
Thank you. Is there a way to check with them without the hard hit? Does it help that I've had my CC with them and been very good with utilizing and paying early/on time?
Not likely. Consumers can't pull an auto-enhanced FICO from anywhere without the help of a lender. There are some banks and CUs out there though who can use a soft inquiry to see if you are pre-approved, though they don't usually use an auto-enhanced FICO.
Having other credit with the lender may or may not help. It's a YMMV per lender.