You are unlikely to avoid a Hard Pull from PenFed in this situation. If it's purely for the purposes of loan shopping you have to authorize the hard pull. However, if you're trying to have funding in hand mainly for shopping the (actually, any) actual car, PenFed DOES do that.
PenFed is one of the few lenders that provides a "no-questions asked" check for the purposes of an auto loan up to a specified maximum amount at a predetermined, single interest rate. They do have higher underwriting requirements for this option (I think the cut-off is 680 on their FICO vs. their normal minimum of 620 for pre-specified vehicle loans), but this allows you to purchase classic cars and older vehicles most lenders exclude once they become 7-10 years old. I could have bought a Model T if I wanted to as long as it had a VIN and it was insured.
I think the check is good for 90 days (could be 60, not sure), but that lets you buy from private sellers or any dealer with funding secured and maximum flexibility - you can buy literally anything street legal up to that loan amount they preauthorize you for.
The hard pull is likely unavoidable but HPs aren't the end of the world especially if you concentrate them together for auto loan shopping. You also have the option of letting the loan offer & check lapse and won't have a new account if you can find better loan terms. Figured I'd mention this if it applied to what you want to do; probably not though.
