Scania R470 Fuel Consumption

ellies dad:
Unbelievable mpg figuires,i know of one n.irish company which had 1854 mercs and never pulled more than 6 tonne.6.5 mpg was the norm,and it wasnt the mercs cos now they have changed to R480 toplines same work same drivers and weights.the figuire now is 7 but they reckon its cos the scanias are opticruise.

I don’t know about Mercs, but as R470 and it’s updated version R480 are turbocompound engines they are less economical at low weights than conventional turbocharged engines. Reason behind this is that the second turbocharger (aka turbocompound) adds engine internal resistance even when it’s not contributing any output power and at low weights, like with those 6 tonne loads, you barely ever need all your horses which makes turbocompound only to “idle” most of the time. That idling of course ain’t free and engine have to work little harder to outcome resistance of idling turbocompound which equals to increased fuel consumption.

On the other hand, whenever you really utilize turbocompound, engine does have noticeably better efficiency at that moment than conventional engine giving same output power. This is reason why turbocompound engine gives better fuel figures when running heavy most of the time as engine is at it’s most efficient zone most of the time. This, of course, applies only as long as driver is sane enough to not use that extra power at wrong way which most likely ends to increased fuel consumption. This is possible and likely even with these automated gear boxes.