Abstract: This invention provides alkoxy acetic acid derivatives of general formula I: ##STR1## wherein R is the residue of an amine, an aminoalcohol or a polyol linked to the or each --CHR'--CO-- moiety via an amide or ester linkage;R' is hydrogen or a C.sub.1-4 alkyl group;R.sup.1 is an optionally substituted hydrocarbyl group of 1 to 300 carbon atoms;one of R.sup.2 and R.sup.3 is independently selected from hydrogen and optionally substituted hydrocarbyl of 1 to 10 carbon atoms, the other of R.sup.2 and R.sup.3 being independently selected from optionally substituted hydrocarbyl of 1 to 10 carbon atoms;m is from 3 to 200;n is from 0 to 20, provided that m/n is at least 1; andp is from 1 to 5; a process for their preparation; and their incorporation in additive concentrates and fuel compositions for internal combustion engines.