With the doppelganger Starsky and Hutch driving around in an identical Ford Torino to Starsky's, an extra Torino was needed for the production of this episode (at least three were used during filming the story). But one of the Torinos doesn't quite match the other(s). The most noticeable difference (especially for non-car enthusiasts) is that the back section of the white stripe, which it curves up towards the roof, is angular, not the usual rounded stripe. The extra car is also sitting lower on its suspension than the 'jacked-up' regular version, and instead of the 'Appliance brand' slotted dish rims on the TV car(s), this one has 'Keystone Klassics', a totally different style of wheel. Plus, this car has raised white letter tires, and the regular TV cars were always blackwalls.
The different car (identifiable by the 'angular stripe') can be spotted at various points through the episode; changing to the regular-version Torino and back again between different shots for both Starsky and Hutch, and their impostors' scenes! When (the real) S & H get the call to go the massage parlour it can clearly be seen, and can it again when the fake S & H are getting out of theirs a few minutes later. It's also prominent during the chase at the climax, but again flips back and forth between shots!
It's quite feasible that the fake Starsky and Hutch's car wouldn't be exactly identical to the original, but the fact that the real Starsky's genuine model is also seen to suddenly flip versions is less forgivable!