gallons per hour / RPM - no load

[Hondaaccord98]

I was wondering how much energy the engine expends just keeping itself alive at different RPM's. I've got a Scangauge so once when the engine was warm I checked GPH (gallons per hour) at various RPM's with the car in neutral. Actually what I did was gradually increase the RPMs and note when the GPH moved to a higher value. This is an imprecise method because the throttle (without load) can't accurately control RPM but none the less here's what I got. This is with a 98 Honda Accord 4 cylinder vtec 5 speed manual:

GPH RPM
0.3 1070
0.4 1180
0.5 1580
0.6 1880
0.9 2900
1.0 3050
1.2 3400


I made a graph out of the results and made it linear. 70 mph is a common speed for me and the engine is turning 2700 rpm there which uses 0.82 GPH (according to the graph) just keeping itself alive. This car gets around 36 mpg at this speed which is 1.95 GPH.
Amazingly 42% of the gasoline burned at 70mph is just keeping the engine alive ... only 58% is used to motivate the car. I would surmise that at higher speeds the percent to keep the engine alive would be a smaller percentage of total gasoline used and at slower speeds it would be a greater percent.
This is the reason burn and glide gives such an increase in mileage ... during the glide portion, with the engine off, this keeping the engine alive inefficiency is eliminated.