Last Updated Jul 20, 2011 3:39 PM EDT
Car-shopping site Edmunds.com has done the math on monthly costs at recent gas prices; it recently ranked wallet-busters and super-savers in different categories of 2011 models. The range of costs was startling: Within the same size class, the thirstiest can run up a gas bill two to three times that of the best gas sippers.
Edmunds assumed you drove a typical 1,250 miles a month (15,000 a year). Its analysts did these rankings after the national average price of gas calculated by AAA rose above $3.50; it is now nearly $3.70 (and above $4.00 in California). Obviously, monthly costs change as gas prices do.
But the vehicles' relative rankings won't change much - and the Edmunds calculations give a good snapshot of how much an efficient car can brighten your gas budget. Additionally, these rankings provide comparable costs for alternate fuels such as natural gas and plug-in electrics.
This ranking shows the most intriguing range of costs. The plug-in Nissan Leaf shows monthly charging costs of just $41 a month; its competitor the Chevrolet Volt - which uses some gas for a back-up generator - takes $58 in monthly costs. (See Chevrolet Volt: What Will the Car of the Year Really Cost You?) The Honda Civic GX, fueled by natural gas, would cost $46 a month if you had a home fueling station and $87 a month if you bought from commercial stations. (See Save Money on Gas: Buy a Natural Gas Fueled Car). The monthly gas bill for a Toyota Prius hybrid (51 mpg city, 48 highway) - at left - would be $89.
Ranked worst for monthly gas costs among small cars is the Subaru Impreza WRX STI, a high-performance all-wheel drive car with a 2.5-liter turbocharged four-cylinder engine. With just 17 mpg in city driving, 23 on the highway, its monthly gas bill would be $249 - six times the cost of the Nissan Leaf and 2.8 times that of the Prius.
With no plug-ins in this category, the lowest mid-size fuel costs belong to the Ford Fusion Hybrid, at right. Ranked by the EPA at 41 mpg city, 36 highway, its monthly fuel bill is $108. Just behind is the Hyundai Sonata Hybrid (35 mpg city, 40 highway) at $111.
Most costly in this segment is the Volkswagen CC VR6 -another all-wheel-drive performance model with a six-cylinder engine ranked at 17 mpg in city, 15 highway. Its monthly fuel bill is $225 - just more than twice that of the hybrids.
Hybrids rule here too, with the Ford Escape Hybrid (34 mpg city, 31 highway) topping this list at $132 in monthly fuel costs. That's half as much as "worst" pick: off-roading champion Jeep Wrangler (15 mpg city, 17 highway), at $263.
As Edmunds analyst John O'Dell notes, "Unless your daily commute is across the Rubicon Trail, it might make sense to bank the $131 a month you would save with a Ford hybrid and use it to rent a Wrangler for your annual two-week trek into the wilderness."
The Toyota Highlander Hybrid (28 mpg city, 28 highway) tops this list at $158 monthly fuel costs but the Chevrolet Equinox, at right, with a standard gas engine ranked at 22 mpg city, 32 highway, is not far behind at $172.
The four-wheel-drive Nissan Pathfinder, with a 5.6-liter V-8 engine rated at 13 mpg city, 18 highway, is worst at $343 a month - among several Nissan, Toyota Mitsubishi and Mazda models in that part of the rankings. "You know it's a brave new world out there when a list of the most fuel [efficient] midsize SUVs includes a domestic model - the Chevrolet Equinox - while the worst fuel economy in the segment is being racked up almost entirely by import models," says analyst John O'Dell.
Of course, saving on fuel is only one aspect of automotive budgeting. The initial cost of that high-mileage car may take too long to pay back from gas savings. (See The Best Cars for High Gas Prices). But with the prospect of gas prices remaining high for the foreseeable future, it makes sense to at least consider cars with low fuel costs.
Photos courtesy of the manufacturers
More from MoneyWatch: