You don’t have to pay a premium for a hybrid car or endure the inconveniences of a diesel or plug-in electric vehicle to get great mileage. Automakers have been working hard to improve the fuel efficiency of conventional gas-powered vehicles. They have to—government regulations will penalize carmakers that fall short of a fleet-wide average of 37.8 miles per gallon (mpg) starting with the 2016 model year. Here are some excellent gas-powered cars that already reach or exceed 40 mpg (on the highway)…

SUBCOMPACT CARS

Chevy Sonic. The same Chevrolet engineering team that works on the powerful Corvette sports car handled the tuning of the Chevy Sonic economy car. It shows—this is one subcompact that’s a lot of fun to drive. To get 40 mpg on the highway, you will have to select the Sonic LT or LTZ model with the manual transmission and the optional 1.4-liter turbocharged engine.

That’s a smaller engine than the 1.8-liter four-cylinder in the base Sonic, but both deliver the same 138 horsepower (hp), which is quite a bit of power for this category. (The 1.4-liter engine adds $700 to the price.) The Sonic comes with more amenities and safety equipment than most cars in its price range and feels roomy inside for a subcompact.

The Sonic gets 29 mpg city/40 mpg highway with the 1.4-liter engine and manual transmission. Models with the 1.4-liter engine start at $16,565. Models with automatic transmissions are likely to get around 26 mpg city/35 highway and start at $13,865.

Ford Fiesta. This well-made subcompact’s ride is comfortable, its handling is agile and its quality of construction, styling and list of standard features are impressive. The Fiesta’s 1.6-liter four-cylinder engine produces just 120 hp, but it doesn’t feel underpowered. Opt for the SE model with the optional Super Fuel Economy (SFE) package if your goal is to reach 40 mpg on the highway. That will add $695 to the price. The Fiesta gets 28 mpg city/40 highway with the SFE package. The SE with the SFE package starts at $15,365.

COMPACT CARS

There are four appealing cars in the compact-car category that reach 40 mpg.

Ford Focus. The Focus is well-made, well-equipped and quite stylish inside and out. Its 2.0-liter four-cylinder engine produces an impressive 160 hp. Put that power together with sporty handling and a controlled ride and the result is a car that’s very enjoyable to drive. Some Focus drivers have complained about excessive road noise and an automatic transmission that can be clunky at low speeds, but even with those flaws, this is one of the most impressive vehicles in the category. Opt for the SE model with the SFE package if your goal is to reach 40 mpg on the highway. It will add $495 to the price. The Focus gets 28 mpg city/40 highway with the SFE package. The SE with the SFE package starts at $17,995.

Hyundai Elantra. The Elantra is an excellent value that provides a comfortable ride and impressive standard features, such as remote keyless entry and heated side mirrors, for a very reasonable price. Elantra buyers need not ante up for a special fuel-efficiency package to reach 40 mpg on the highway—the base-model Elantra sedan, with its 1.8-liter, 148-hp four-cylinder engine, achieves that efficiency target. On the downside, the Elantra’s throttle response is a tad sluggish, and its interior feels a bit cheaper than that of the Ford Focus. The Elantra gets 29 mpg city/40 highway. The price starts at $15,345.

Mazda 3. This is the most exciting car to drive in the affordable compact-car category. Its handling is precise and responsive…its ride firm but comfortable. As with most Mazdas, the steering is excellent—drivers feel very connected to the road. Some complain about the Mazda 3’s road noise, however, and it’s not the roomiest car in the class. Opt for the 3i Touring sedan with Mazda’s new 2.0-liter four-cylinder 155-hp Skyactiv-G engine if your goal is to reach 40 mpg on the highway. (The comparably equipped hatchback falls just short of 40 mpg.) Mileage is 28 mpg city/40 highway for the 3i Touring sedan with Skyactiv-G, starting at $19,495.

Chevrolet Cruze. The Cruze is well-equipped, fuel-efficient and roomy by compact sedan standards—it has seven cubic feet more interior space than the Ford Focus. This car is for those who like a calm, quiet, controlled and comfortable motoring experience, not those who like to push their cars hard through corners. It’s well-built and attractive inside and out. Opt for the Cruze Eco model to get 40 mpg on the highway. It’s available only with a manual transmission. Other Cruze models with automatic transmissions tend to deliver 36 to 38 mpg on the highway. The Eco’s 1.4-liter turbocharged four-cylinder engine produces 138 hp—that’s less power than the other compact cars on this list but enough to get you down the road just fine. It gets 28 mpg city/42 highway for the Eco model, starting at $19,325.

HIGH-MPG VEHICLES IN LOW-MPG CATEGORIES

Two fuel-economy all-stars, even if they can’t quite deliver 40 mpg…

Hyundai Veloster Turbo. If you’re in the market for a powerful, sporty car that’s still fuel-efficient, consider the Veloster Turbo, due out this summer as part of the 2013 model year. This two-door hatchback will offer attractive looks, great handling and an impressive 201 hp. It gets 27 mpg city/38 highway and starts at around $21,500.

Mini Cooper Countryman. This well-made four-door crossover is much smaller than a true SUV but still provides 41.3 cubic feet of storage space with the rear seats folded down. The base model’s 1.6-liter four-cylinder engine produces 121 hp. That’s low but sufficient for a vehicle this small. The base model with manual transmission gets 27 mpg city/35 highway (25 city/30 highway for the automatic). It requires premium fuel. Price starts at $21,750.

Source: Karl Brauer, who recently launched www.TotalCarScore.com, a Web site based in Camarillo, California, that combines various authoritative car reviews into a single score. He previously served as editor in chief of www.Edmunds.com.