Old scrappy piece of junk with a quite healthy stock engine. Factory says 6-7 litres / 100km (aprox. 35-40 MPG) but most owners are more familiar with 7-8 L100 (30-35 MPG).
I average around 4.6 L/100km (50 US mpg) by Burn & Glide with engine shut-down + Driving Without Brakes.
Not much really, mainly driving style. Have just installed buttons with a relay box for easy engine on/off on the shift-stick. LED driving lights and rear lights to save battery during coasting and stops with engine shut off. High tire pressure. 20-25% ethanol in gasoline improves combustion in old carburetted engines. Ethanol is also cheaper than gasoline.
Installed a Simon's Ralley 2" full-flow exhaust system and widened the front rims for 195/65R15 tyres in May 2016. A nice and mighty noise and higher cornering speed was the result, -without any negative impact on fuel consumption.
The Phantom Blot is slowly turning into a rat rod so my earlier plans for fuel efficiency instrumentation and aerodynamic attachments is put on hold for another Saab project. So far my "roddification" have not worsened the fuel consumption... :-)