Kama gari lako lina tachometer (rev counter) wewe iangalie hiyo ndipo utakapopata majibu kwa haraka. Spidi ya engine ndiyo inayotoa mwongozo wa ulaji wa mafuta kwa sababu huashiria ni nishati kiasi inahitajika ichomwe ili kuweza kutoa nishati nyingine. Ukiwa katika mwendo kasi mdogo, matumizi ya kiyoyozi ndani ya gari huongeza ulaji wa mafuta kwa kiwangi kikubwa. The Impact of AC on fuel consumption at higher speeds say in excess of 80km/hr when the engine is already working hard seems to be less pronounced than at lower speeds.
Kwa kujaribu tu, washa gari lako kisha uangalie tachometer inavyosema with and without AC bila hata ya kuanza kutembea. Vitu vingine vinavyochangia ulaji wa mafuta vipo vingi tu kuanzia injectors, silencer ya gari, usafi (si wa macho) wa engine, suspension, vehicle height and mass, tyres etc.