[CaptainDoggles]

Originally Posted by IvanK

In some rough and dirty super quick Flight testing these are the Fuel Flow figures I got.

Spitfire IIA
Climb +4/2800RPM 72gal hr. Book figures 94Gall hr
Cruise +2/2600RPM 60gal hr. Book figures 78 gall hr

BF109E4
Climb 1.35/2350 RPM (AUTO) 480Ltr/hr (106Gall/hr)
Max Cruise 1.35/2400RPM 360 ltr per hr

Blenheim IV
I4000ft at +3Lbs Boost Full Coarse pitch. 30 Gall/hr per engine i.e 60Gall hr total
Documented values 57Gall hr per Engine Total 114 Gall/hr

Method was taking Tool tip displayed values over a number of samples (using a 5min sample) then averaging the result for each type and situation.
Tool tip I think only displays Fuel qty to within 10units so a longer sample time (than 5 mins) would give better results.

EDIT 20 Min Flight Test.
BF109E4 1.35ATA/2350 AUTO Oil/Coolant Rads full open, Start Fuel 340Litres, Level flight Sea Level
After 10 Mins Fuel Remaining 280Litres (Fuel Flow 360Ltr/hr)
After 15 Mins Fuel Remaining 260Litres (Fuel Flow 320Ltr/hr)
After 20 Mins Fuel Remaining 230Litres (Fuel Flow 330Ltr/hr)
Average 336Ltr/Hr

Are these at sea level?