Can any body give me a formula for calculating the fuel consumption with respect to speed and gradebility?

Question

CAN ANY BODY GIVE ME A FORMULA FOR CALCULATING THE FUEL CONSUMPTION WITH REPECT TO SPEED AND GRADEBILITY.ASSUMING 2% AS A ROLLING RESISTENCE OF THE VEHICLE

Answer 1

C = fuel consumption

V = velocity or speed along road

t = time for your trip

S = SFC, specific fuel consumption (varies with engine, temp, and load, but usually about 0.4lb/HP)

r = density of fuel, 5.8lb/gal for gasoline, maybe 6.5? lb/gal for diesel

P = power from engine

F = total resisting force

Fd = drag force

Fr = rolling resistance

W = truck weight

G = grade in % (-% for downhill)

A = frontal area of truck

Cd = drag coefficient

C = Dist/Fuel used

    = V * t / {[P] * S * r * t)}

Time cancels out, top and bottom:

C    = V / {[F * V] * S * r}

Force is drag force + rolling resistance + force to go uphill:

C  = V/{[Fd+Fr+W*(G/(√(1+G²)) * V] * S *r}

Now, where rho is air density,

Fd = (A * Cd * rho) * V²

In practice, just determine a number for the product of all three, as noted below.

Rolling resisance should be estimated, needs to be in lb or similar.

To determine estimates for rolling resistance, get mileage at two or 3 speeds, level ground. Put actual mileage in formula, try with different values of (A*Cd*rho) and rolling resistance to get decent fit.