A photoelectronic fuelmeter has been developed to meet the need for a dependably accurate, precision instrument for measuring motor vehicle fuel consumption under either static or dynamic test conditions. It is useable under all operating conditions encountered either on city streets or turnpike highways. Automotive fuelmeters heretofore available have not been satisfactory for us in studies of vehicle fuel consumption as affected by highway and traffic conditions for one or more reasons. This new instrument is a continuous sampling system which retains the advantages of the buret type of fuelmeter but uses an electronic means for detecting and presenting, as simple digital readings, actual fuel consumption information. The basis instrument is usable for gasoline-powered vehicles and, with the addition of an auxiliary device called a deductor, is equally useful with diesel-powered vehicles. The fuelmeter may be coupled with a device for measuring distance travelled and thus provide miles-per-gallon information.