Based on a semi-controlled field test, 26% of the total car population can be expected to exhibit severe carburetor icing under conditions of 40-60 F and above 80% relative humidity. The best of today's anti-icing additives have done little more than offset the increased fuel volatility trend over the past 10 years. Mechanical design is a most effective means of controlling the problem. Further progress in additives is dependent upon good evaluation techniques, the best of which is in actual cars in all weather chassis dynomometer facilities or in properly controlled field tests. Beware of laboratory engine tests which can be misleading.