There are already sites that talk about Honda Insight drivers getting over 70MPG and how they do it. Some is practical and some is illegal and quite dangerous (but you can brag about being the mileage king/queen). If slowing things down creates more traffic (and traffic jams) then what have we saved?
People buy vehicles to meet their needs and wants. Somtimes, they don't put a lot of thought into how much it costs to operate it (let's face it an oil change on the Z3 is not cheap even if you DIY) so now they are in trouble because gas has doubled in price. Unfortuantely, gas isn't the only thing that has gone up so we're feeling it in other places too.
I'd keep playing! I don't think the heavy stuff will be coming down for quite a while!