Ford Fiesta (© Ford Motor Company and Wieck Media Services, Inc.)

Ford Fiesta

Achieving 40 mpg on the highway has been the holy grail of fuel efficiency ever since the hybrid went mainstream at the turn of the century. And until recently, gas-electric vehicles were pretty much the only vehicles on the road to achieve that lofty goal here in the United States. But that's about to change. Automakers have stepped up their efficiency game in the past couple of years by offering capable and comfortable gasoline-only vehicles that are almost as miserly at the pump as their hybrid brethren.

How, you ask? Some rely on special option packages that include aerodynamic enhancements and specialized equipment such as slick underbody kits and low-resistance tires to maximize a gallon of gas. Others combine tried-and-true engineering with emerging technologies such as turbocharging and start-stop functionality to enhance efficiency.

Bing: Gas Prices

Regardless of how these frugal machines do it, they are doing it, which is important for the future health of the auto industry. More than 97 percent of all new car buyers in the U.S. still purchase vehicles powered by fossil fuels alone, according to J.D. Power and Associates 2011 US Green Automotive Study, and possibly even more importantly, among active new car buyers, fuel economy — followed by quality, safety and price — is the most important consideration when deciding on which vehicle to purchase, says a recent Consumer Reports survey.

We don't see these preferences changing any time soon as gas prices are hovering around $4 per gallon and primed to climb even higher as the summer progresses; the cost of hybrids is on the rise because of vehicle and parts shortages after the March earthquake and tsunami in Japan; and economic uncertainty in the U.S. continues

If you're looking to squeeze as much as you can out of your monthly budget and either don't have the coin for a new hybrid or the desire to own one, here are our picks for the five most efficient gas-powered rides on the road today.

2011 Chevrolet Cruze Eco

Cost: $18,425
Fuel mileage: 28 mpg city/42 mpg highway

The impressive frugality of the Chevrolet Cruze Eco comes by design, not as the result of an options package. Extreme measures in the form of thinner sheet metal on key body panels and advanced, lighter-weight welding techniques are joined by the deletion of interior trim items, aerodynamic optimization and powertrain tricks to extract maximum mileage from each drop of gas.

Under the banner of wind-cheating, Chevrolet engineers redesigned the car's nose to reduce drag, enclosing the upper grille area. They also developed motorized shutters in the lower front air intake that close at highway speeds, again to reduce drag.

GM further improved aerodynamics by dropping the ride height by 0.4 inch and installing underbody panels that smooth airflow under the vehicle. Other tricks include lightweight wheels that save 5.3 pounds over the Cruze LT1 trim and the prerequisite low-resistance tires.

In the end, the Cruze Eco is 200 pounds lighter than the standard LT1 trim, which allows its turbocharged 1.4-liter 138-horsepower 4-cylinder engine to deliver 5 mpg more in highway mileage. The Eco trim employs a 6-speed manual transmission exclusively, and although it is currently available only as a sedan, GM has been displaying an attractive hatchback version on the auto-show circuit.

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2011 Ford Fiesta SFE

Cost: $14,520
Fuel mileage: 29 mpg city/40 mpg highway

The Fiesta flexes its mileage muscle when ordered with Ford's optional Super Fuel Economy package. The $695 SFE package includes underbody aerodynamic panels and block-out plates on the lower grille to optimize airflow over the nose of the car. Aero-sculpted side mirrors and grooves cut into the taillights further reduce drag. Rolling stock consists of 15-inch wheels and low-resistance tires.

A 6-speed automatic is the only gearbox available for SFE-equipped cars, and modifications to the Powertrain Control Module in SFE trims alter shift patterns in the name of extreme fuel efficiency. All Fiestas are motivated by Ford's 1.6-liter 120-horsepower Duratec 4-cylinder engine.

The all-new 2011 Fiesta is the only vehicle on the list that can be ordered in hatchback configuration. Going this route bumps the car's cost to $15,520. Drivers who want a tad more room may want to consider the 2012 Focus SFE from Ford, which is also rated at 40 mpg highway.

Watch Video:  2011 Ford Fiesta

2012 Honda Civic HF

Cost: $19,455
Fuel mileage: 29 mpg city/41 mpg highway

The Civic HF (High Fuel economy) is the most expensive of this group. Even so, it is still priced at less than $20,000. The Civic HF cuts a familiar path en route to its fuel-efficiency nirvana, with underbody paneling, a lowered suspension and low-resistance tires. The HF features unique, lightweight wheels and a proprietary rear spoiler, but technology also plays a vital role in its miserly manners. Honda's Eco Assist system serves as a high-tech co-pilot, maximizing the efficiency of car and driver alike.

Pressing the large, green Econ button activates Eco Assist and puts the Civic HF on alert as it monitors critical systems, looking for ways to minimize losses by controlling the engine and other energy-consuming systems. Eco Assist improves driver performance with an array of bar graphs in the gauge cluster. The goal is to work the throttle gently, keep the graph in the green and reap the maximum mileage. The function can be easily turned off if it becomes annoying.

The Civic HF is available only as a sedan, and is powered by a 1.8-liter 140-horsepower iVTEC 4-cylinder engine, backed by a 5-speed automatic transmission.

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2012 Hyundai Elantra

Cost: $14,945
Fuel mileage: 29 mpg city/40 mpg highway

The Elantra sedan posts its big mileage numbers without really trying. By that we mean Hyundai offers no special packages, no aerodynamic body panels, not even low-resistance rubber. The Elantra uses its lightweight nature and a drag coefficient of 0.28 to get into the 40-mpg club. The entry-level GLS is joined by a more upscale Limited trim ($20,195) that also returns 40 mpg.

The Elantra is all-new for 2011 and, drag coefficients aside, it is the most stylish miser on our list. Its swept roofline and wide haunches give it that passive-aggressive look that makes bystanders look twice.

Under the hood, a 148-horsepower 1.8-liter 4-cylinder engine generates the most muscle of the bunch while providing a whopping 30 percent reduction in weight compared with the previous Elantra engine. The Hyundai is the only car on the list to offer a choice between manual and automatic transmissions.

Compare: Hyundai Elantra vs. Ford Focus vs. Honda Civic

2011 smart fortwo

Cost: $12,490
Fuel mileage: 33 mpg city/41 mpg highway

The smart fortwo is miserly driving in its rawest form, and the car makes many unnecessary compromises in its quest for efficiency. The fortwo's "golf cart on steroids" size and styling has become obsolete as other manufacturers now generate similar or better fuel-efficiency numbers while retaining all the seating, comfort, convenience and versatility of a conventional automobile. The base fortwo, the pure coupe, is joined by the passion coupe ($14,690) and passion cabriolet ($17,690). All three trims deliver 41 mpg highway from their 1.0-liter 70-horsepower inline 3-cylinder engines.

The smart is the cheapest of this grouping, and if you want your vehicle supersmall and maneuverable, it is your ticket to ride. We think its minuscule size and egg-shaped design take it out of contention for many buyers.

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Evan Griffey served as an editor of Turbo & High Tech Performance, a pioneering publication about sport-compact tuning. Today Griffey freelances for Import Tuner, Sport Compact Car, Car Audio and Siphon.