This Olds was one of the earliest manufacturer-ecomodded cars I had read about.
I
compared it to the Metro XFi:
They modified several of the same things that engineers would later do in the Metro to create the XFi, including using a taller final drive ratio and - surprise, surprise - a special "efficiency cam".
Noting that "internal engine friction increases roughly as the square of rpm, and is relatively unaffected by the load on the engine or the degree of throttle opening," the goal of the Oldsmobile's engineers was to create a car with good torque at low RPM - just like the XFi.
To permit loafing the engine along while maintaining acceptable driveability, the Olds engine included several other improvements from the stock motor
[which they don't describe] , but of all the mods, "the camshaft is the key."
Like the XFi's cam 25 years later, the economy cam in the Olds used lower lift, shorter duration, and advanced timing. As a result of the increased lift rates, both the Olds and the XFi also have somewhat less peak power compared to their less efficient siblings (because the redline is lowered due to the potential for valves to float at high RPM).