You can get an idea about the film mentioned, by going to most any higher end car dealer. A number of times they have a car on the floor with the plastic film on it. I can understand your reluctance. I think it would be kind of difficult to fit to the 113. The newer cars, with the more aerodynamic bodywork, and body color bumpers, etc, are a very good application. There is not all that much paint around the grill on the 113, and what is there, would make cutting and trimming of the film a rather interesting affair.
For a long distance drive, a regular bra is a decent option, however, the black grill inserts are susceptible to chips and you wont be able to cover those.