Daddy Jack's has a very good tenderloin but atmosphere lacks considering it is in a small strip shopping center and is a bit too corporate for my taste.
Part of the experience, since there are so many good tenderloins, is the atmosphere. Muldoon's for instance is an Irish Pub though too a bit too cute. It is located further up Meridian Street in old Carmel. BTW, the drive up and down Meridian Street is a nostalgia treat of Indianapolis in its heyday of old mansions.
Bourbon Street Distillery at 501 Indiana Ave. downtown has character although the tenderloin I had there was a bit greasy for my taste. It just could have been the fryer cook that day. http://web.mac.com/davydd...ndianapolis%2C_IN.html
If you want the Mecca experience of Indy, The Flag Room at Brickyard Crossing on the Indianapolis Motor Speedway grounds would be a good choice. Their consistency is lacking. I had average there and I also had the biggest tenderloin I ever had in Indiana there.
Another little bit of Indianapolis history would be Plump's Last Shot in the Broad Ripple neighborhood. It is a restaurant in a converted house. Excellent tenderloin and interesting neighborhood. Probably a better place in warm weather so you can sit outside on the patio with the dog lovers. Dogs are welcome there on the patio and it is a literal zoo.
My tenderloin photos of Plump's Last Shot and Daddy Jacks have been used by newspapers around the country. They evidently were deemed photogenic and representative of a good tenderloin. Their tastes backed them up.