Bigelow picks up a rental car shortly after arriving in Los Angeles. CitySleuth scoured L.A. for this site for too long before thinking of checking out San Francisco. Wouldn't you know it, that's where it was filmed!
Then ... He picks up the car on an open lot. Take a look at the building across the street in the background ...
... and Now, here's that building today, on Washington Street at the corner of Van Ness Avenue. Back then it was the J E French Dodge dealership (you can see part of the Dodge sign above at top left and again in the vintage photo below). The building's auto tradition continues - it now houses the Academy of Art University's Auto Museum.
This would place the car rental lot on the 1900 block of Van Ness (map), confirmed by the ad below from a 1953 publication. The lot belonged to the Stanway Motors used car dealership, proprietor Stanley Strauss, which occupied the whole west block between Washington and Jackson.
... from a vintage photo ... on a historical note, here's the 1900 block of Van Ness in 1946 as it was before (regrettably) being demolished to make way for the used car lot. Look at that wonderful house on the corner, the Silas Palmer mansion, across Washington from the Dodge dealership described above.
... and here's a closer look at the Silas Palmer mansion. Why did it have to go? What a waste!
... and Now, below is a recent look at the same block, residential once more but a poor substitute for its former self. This is progress? At least the street lamp-posts survived.
Then ... As Bigelow drives off the lot there are three businesses clearly visible across Van Ness, one of them being The House Of Prime Rib.
... and Now, the same view today still has The House Of Prime Rib doing business at the same location, 1906 Van Ness. It first opened in 1949, just one year before the movie was released. The exterior of it and its neighbor has been painted in a faux stone finish. On this block too the old street lamp-posts are still there.