I think someone is confusing engine size and power rating with engine efficency. A 216/235/261 has to be one of the most terible designs ever as far as efficency is concerned. Low compression, long log type manifolds with both individual and siamesed ports, runs at a low temperature, heavy recipricating parts and valve train, oil drain back falls onto moving parts, temperature gradient varies widely from front to rear, plug location and chamber design not the best for flame propagation, and I'm sure points that others can bring up. darn, I love them but will NEVER see the day they deliver 25+ economy with any gearing or tire size known to man.
