Factory BK - 12 model 1386 CC. ( C - model )
Tires size, front 165/70R14 81s
Tires size rear 165/70R14 81s
Mininal requirement 95 factory. (42L Full tank cap)
Other factors like climate difference ?.
For sure 98 shell will give you more Mileage
(Subjective to modifications of cars, the comparrsion is base on
factory specs ). Average shows 98 gives more mileage and vpower
provides more torque. Basic street rules, always pump 20 L / 42 L.
EVery L of pertrol is 1kg + -. It does make a difference, car is
lighter, lesser drag and lesser petrol required.
Do the math, my half tank 20L is abt 12 km +- / per Lit. ( abt 270
km +- another 20km more after amber light appears ). Rims is
running on 16 inch and car weight 
Stock car curb weight; 975kg) + 20kg (bodykit) + 60 kg
(SP)+ 25kg ( ICE ) + 40kg ( RIMs) = 1120 kg +-. For sure i am
running abt 11-12 km per lit.
With 98 bhp ( 1120KG / 98 ) = 11.42 kg per horse pull.
On stock, 98 ( 975KG +- / 9
= 9.9 kg per horse pull.
Dun believe you try pump half tank and measure if your mileage; 2 x
half tank of 20L each time. Per 270 km of 20L + 20 reserve = 540km.
So on full tank i am getting abt 540 km / 40L +-. Try 98 shell. Or
by bumping full tank at one go ! and see if your ride can achieve
more. Try it on your own, this is my own car specs calulation. Try
20 L how far for 2 x tank + 20km reserved once amber appears
and
Add together the total. At yr 3rd time you pump full and drive
until the amber light appears + 20km more. See which one will give
you more savers.
Another way to get yr $ worth try pump petrol at night or in the
morning, you will lose abt 3%- 6% when you do it in the afternoon.
Savings of a few cents if you want it.
To each it's own ?
