Control of sulfur in gasoline may be required because of sulfate emissions when using three-way catalysts. The sulfur content of gasoline is primarily a function of the type of crude processed. There is a trend toward processing more high sulfur crudes due to crude availability. Reducing sulfur to about 150-300 ppm will cost about 2-3¢/gallon of gasoline and an investment of $3-5 billion in 1979 dollars.