Quick answer: the paperwork depends on whether probate is open. In probate, the legal representative signs the title over directly. Without probate, a notarized affidavit does the same job.
The title can never say "the estate"
If the estate is in probate
Bring letters of appointment naming the court-appointed legal representative, the vehicle title assigned by that representative as "seller" on the back, a completed odometer and damage disclosure, and the Application for Certificate of Iowa Title (Form 411007).
If there's a will but no probate was opened
Bring the decedent's original title if available, a copy of the death certificate, a notarized Affidavit of Death Testate (Form 411083) signed by the person named as beneficiary in the will, and Form 411007.
Fees waived for a surviving spouse
If ownership transfers to a surviving spouse, title fees are waived, along with any available exemptions that apply to that specific transfer.
A local probate attorney can review your estate — many offer a free consultation.
Any Iowa county treasurer's office processes these transfers — residents can use their own county or a contiguous one, with Polk County and Linn County among the highest-volume offices.