there no such difference price between 14 inche n 15 inche wheels hardly few hundred rupees not more
More the diameter of the wheel , width of rim needs to be proportional to it. With reduction of rim diameter , logically width also needs to be reduced , this in turn ensures a fitment of tyre with lesser width .Lesser is width of tyre lesser is rolling resistance hence better FE despite the 75bhp engine fitted on 1200+ kg car.
So overall effect is , FE is maintained and similar when compared with FE of 90 hp Linea despite same weight.
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If a classic's owner decides to fit a 15 \16 inch rim and tyres he would face a definite reduction in FE unless he goes for 15 /16 inch rim(say 4.5 -5 inches /tyres(165 -175 mm wide) with lesser width but then the handling would go Amby way.
Fiat has deliberately avoided this , else It would have been entertaining to watch how two low sellers(Linea and Amby) fight with each other in taxi market.
So FIAT official rightly said while replying TSIvipul that the car is for both taxi and private buyer.
BTW, reduction in wheel diameter by an inch would reduce the GC by 10 to 12 mm atleast .GC of 174 mm approx is adequate for Indian roads IMO.