I had forgotten about LeMans with Steve McQueen. The Getaway in Stockholm you are referring to is the first one. You couldn't tell other than the sound of the engine
(no turbocharger) but the 911 used in the first Getaway was actually a normally aspirated 3.2L with Ruf exhaust. You can find the information about the car they used on their website.
http://www.getawayinstockholm.com/main.html under FAQ. Nice video too.