Shorter uphill-downhill route, or longer flat?

[sunsanvil]

I'll be experimenting next month where our daily commute becomes a little more regular, but off hand, generally speaking and all that, would one expect to burn more gas going up 2km and down 2km, or take a 5km flat route? ie a difference of 1km (thats not the whole commute, just the section with the option).