Who'd-a-thunk that mile-per-gallon numbers would be important to macho owners of pickup trucks? You can thank spiking prices of gasoline, even before Hurricane Isaac finishes making a wake in Louisiana.

Regular unleaded gas zoomed from the $3.60s and $3.70s per gallon to $4 in central Ohio, where I live, on Wednesday, the day Isaac approached the Gulf Coast and threatened refineries there.

So it's understandable that the domestic Big Three builders of perennially popular pickups have lately been leapfrogging each other in making claims to mpg supremacy.

The latest is Chrysler Group, whose 2013 Ram 1500 has a powertrain that will deliver 18 mpg City and 25 mpg Highway, according to EPA testing that the company quotes.

Like Ford before it, Ram's done it with a modern V-6 engine -- and not just a 6-speed automatic transmission, which both companies began using just a few years ago, but an 8-speed. The tranny, from ZF of Germany, shifts early and often to keep engine revs low at any road speed, if a driver uses a light foot.

Ram's calling this smooth tool "TorqueFlite 8," a name that mostly came from the mid-1950s, when it described a 3-speed slush box (Power Flite was a 2-speed automatic, like Chevrolet's Powerglide).

So, Ram has a TorqueFlite to handle the respectable torque -- 269 pounds-feet -- of the Pentastar V-6, whose displacement is 3.6 liters (220 cubic inches, as we'd say in the '50s) and boasts advances such as variable valve timing and pulse-width modulation of the alternator.

It replaces a less efficient 3.7 V-6. Chrysler's been installing the Pentastar in recent sedans and SUVs and it's gotten raves from car writers for its go-power -- 305 horses in the Ram -- and impressive fuel economy.

The Pentastar slips easily into the big engine bay of the extensively refined (and very handsome) '13 Ram half-ton pickup, and is very nice to drive. The numbers suggest healthy propulsion and it certainly provided that without revving its heads off.

Of course, the short-bed Regular-Cab truck I drove was empty except for me and a driving partner, and I think it'd labor a bit if it were loaded or pulling a trailer weighing anywhere near its 6,500-pound tow rating.

This was at a demo out of Nashville, Tenn., where our hosts had close to 20 '13-model Ram 1500s with either the V-6/TorqueFlite 8 powertrain or the "legendary" 5.7-liter Hemi V-8 (can an engine become a legend in only a decade?) with the current 6-speed automatic.

As we all know, there's no substitute for cubic inches, and the Hemi (with 348 of 'em) is the better choice for its stronger feel and more leisurely operation, as well as its greater work capability (tow rating, for example, is several thousand pounds more). But it won't get the mileage of the Pentastar engine, even when the Hemi gets the 8-speed autotranny early next year.

The smaller 4.7 V-8 will probably continue to be a sad laggard in fuel economy, though there weren't any at the demo and our hosts said nothing about it, except that it'll be the Ram 1500's standard engine. The Pentastar V-6 and ZF combo will be a $1,000 option over an Eight. (That's also true of the Ford F-150's turbocharged EcoBoost V-6, which lists at $750 more than its standard 5-liter V-8.)

Although the Ram 4.7 makes neat V-8 sounds and feels good to drive (or did in the '03 Dakota I once had), it's not especially economical (the most I could squeeze from it was 17 mpg on the highway) because it's a comparatively simple "price-point" engine, as the marketers say. No, the action's with the shining V-6 and the hefty Hemi V-8.

The truck itself helps the mpg numbers with "active aerodynamics" (radiator shutters that close when ram-air's not needed to cool the engine) and electric power steering (which causes less drag on the engine than a constantly running hydraulic pump), among other things.

How long will Ram hold the mpg lead? I'm guessing a year or so, 'til Ford or General Motors or both reassert themselves and reclaim "best in class" numbers. With the Feds forcing higher fuel-economy standards on manufacturers, economy will climb steadily and steeply in coming years.

So will prices, of both trucks and gasoline. We can bet on that.