I liked your analogy of the furnace car vs car costs, but here's the thing. My 900 sq. foot 2 storey shares a common wall with my side neighbour. ( semi-detached they call them here in Ontario) All sales rep say I don't need a big btu furnace. One guy said in the low 20,000 would be all I need.(No heat loss done) All salesmen recommended their smallest 2 stage variable.And when I asked about single stage they again all recommended their smallest. After reviewing all the quotes I noticed that the single stage furnace outputs were the same or lower than the 2 stage on low fire. So I question the validity of the 2 stage furnace when it appears it would never go to the 2nd stage.
It seems like they all want to sell me their top of the line most expensive furnace but know in the heart that it's overkill for this small home.
What do you think airconman and you too baldloonie if you're out there?