For a history of the Total Economy run see
http://www.total.co.za/Os/ossouthafrica.nsf/VS_OPM/1528A077DC41B6D9C1257465003B03B3?OpenDocument
Many people think that the Total Economy Run is an afternoon's doddle. Far from it ...
I assisted a friend on two Runs in the late 70's. The course was set by well-known racing driver Jan Hettema who - at the best of times - drove like a lunatic
In those days it was a three-day event, half of which was on dirt roads. Jan had a Kombi, which he used to survey the routes. Setting the average speed for a stage was pretty simple: if the stage was on tar then the average speed was set at 90% of the legal speed limit; if the stage was on dirt it was 80 or 90% (can't remember which) of Jan's time over the stage. As a result simply to finish a stage without time penalties (for being late) was considered a major achievement.
NB: The roads were never closed off for the rally. So if you were caught in traffic - tough!
The last year that I was there rally champion Sarel van der Merwe announced (in the pub, the night before the start) that the rally was for old ladies (or something similar). The next day both he - and cricketer Clive Rice - managed to roll their cars ..

Sarel immediately humphed off, whilst Clive - now christened 'Roll-over Rice' - stayed and with a smile handled the nick-name and good-natured jokes for the rest of the week-end.
Great fun, but certainly not for sissies !!
Re the cars: all were (are ?) standard off-the-showroom-floor models, i.e. no factory specials. One could (for instance) change tyres, but the tyres had to be the size for the car. No body-work changes etc. The cars all carried three people - driver, navigator and observer. All cars were filled from the same pumps, then had their filler caps sealed.