Injector deposits in a direct injection gasoline engine are reduced by providing as fuel for the operation of said direct injection engine a fuel composition comprising a fuel-soluble compound having the formula (I): wherein R1 and R2 are independently C1-4 alkyl, R3 is a radical of the formula CmH2m wherein m is an integer of 2 to 6, R4 and R5 are each independently (i) hydrogen (ii) C1-4alkyl, wherein R6 is selected from the group consisting of hydrogen and C1-4 alkyls and R7 is selected from the group consisting of hydrogen and C1-30 alkyl, (iv) wherein R8 is a saturated or unsaturated, linear, branched or cyclic, C7-23 hydrocarbyl group or (v) wherein R4 and R5 together with the nitrogen atom to which they are bonded, form a cyclic ring in which further hetero atoms.