I have a Lockheed TriStar Service Digest from the 1976 with all 32 pages decated to Fuel Conservation. Here are some of the fuel penalties from the artical, for missing/damaged seals:
Slats - Missing chord wise interslat seal 5,040 to 5,970 gal per year.
Cargo Door - five square inch effective leak 11,750 gal per year.
Passenger Door - five square inch effective leak 11,750 gals per year.
That's referencing the economic penalty...or in other words what it cost extra to have the seal missing.
What's in discussion here is the performance penalty associated with the missing seal.