Cars Q&A

Hi experts of Cartrade,I would appreciate if you could give me your professional views about my querries for few questions.1st of all,my maruti alto lx gives me only about 10kpl with a/c on,where as other people claim to get 15-17kpl with a/c.Why so much of diifference?How the mileage can be improved! Also plz guide me to select one from polo,beat,i10/i20,fabia1.2,ritz (all petrol). And one from (diesels)comparing maruti swift,polo,ritz, i10/i20.My budget will be 4-5 lacs considering mileage, low maintenance and value for money.Thnx & rgds. Plz note that your early early answer and guidance will be highly apprecited.....Jasvir