We will have a fair number of fairly big vehicles-Suburbans,Tahoes,Pickups on the road in the USA for quite a while.The reason is that used big vehicles are cheap to buy.We are short of money-medical bills-so we sold the Pilot,Prizm,and bought a Suburban.We need-occasionally-a big vehicle to do home depot runs and to buy sell used items funiture, bikes,motorcycles) occasionally and to evacuate for the next hurricane(4 cats,one long legged dog,3 adults-river ridge is a suburb of NO).We can't do what is commonly suggested-rent-because everything is rented when a storm comes.
Many families can only afford one vehicle,and it has to be big enough to get everyone out of town.It isn't used much,so they take the 13mpg penalty everday(what I get in the city driving a 2wd Suburban).A small car-Corolla,Civic would get almost 2x(our Prizm got 23mpg year round city).
The solution for us is a $23000 Prius and a $2950 1998 Suburban.Unfortunately,Many folks can't afford a $27000 solution ,so they buy just the $3000-$5000 big used vehicle.
The problem with most small high tech-diesel,hybrid,electric- vehicles is the initial cost of about $25000+ out the door.For about $17000 out the door you can get a very good-Corolla,Civic,Fit,Focus,Scion-small vehicle that get 25 mpg city-for even less you can get an Aveo-maybe $11000 out the door.Unfortunately,thses vehicles can't haul 5 adults,animals+ a bunch of evac stuff.They can't haul furniture etc either.
Big cheap used vehicles are a better dollars and sense solution for many folks.They can afford-barely-the $100 fillups-because the initial cost of the vehicle-used-is so low.
Car pooling,P&G,and planning trips can make the big vehicles more efficient.The Suburban gets about 60% the mpg that the Prizm(corolla) did.3 people in it,is a lot more efficient than one in a civic.Unfortunately, it is hard to set up car pooling.With gas going up in cost,there will probably be better coordinated car pool efforts-folks could wait at bus stops,and flag down a pool vehicle.No doubt the lawyers,and insurers will toss a monkey wrench in.
Charlie
PS I like the small diesels in cars/minivans-GM makes a 40 mpg Zafira-TDI in Europe.It is a mini minivan like the Mazda 5-roughly 184" long.fairly tall-can carry 6 adults.Unfortunately, it would sell for a bit more than an Odyssey here in the USA.It would be a very sweet road trip vehicle,and an evac vehicle.I think it sells for about $30000 in Europe.GM knows it can't sell it for a profit here-yet.