Look to the top of the fuel economy charts and, if you're not in the market for a plug-in vehicle, it's hybrids that typically top the list.
Cars like the 2012 Toyota Prius C, which currently tops the list, sip gas whether in the city or on the highway, and ultimately they're the greenest way of getting about without going electric.
But what if you don't want a hybrid?
If that's the case, you might be interested in some of the vehicles below, which offer 40 mpg-plus gas mileage on the freeway without having to go down the hybrid path. They won't match hybrids in city driving, but if you typically drive longer distances, they could be the cars for you.
2012 Volkswagen Passat TDI
Topping the non-hybrid tree for highway gas mileage is the VW Passat TDI. Its 2.0-liter, turbocharged diesel can be found in several Volkswagen and Audi products, and in fact we've excluded the others here (the Jetta, Golf and A3 all top the list) just to prevent the list being a VW washout!
At 43 mpg on the highway and 35 combined it actually sips less diesel than its smaller counterparts, despite offering more space for passengers. That makes it a great choice for long freeway drives, where the strong low-down torque, quiet engine and great economy will raise a smile. It's not unknown for diesels to beat their EPA mileage estimates, either...
2012 Chevrolet Cruze Eco
The award for highest-placed non-diesel goes to Chevrolet, with the Cruze Eco. A few subtle tweaks to aerodynamics and gearing, plus an efficient 1.4-liter turbocharged gasoline engine, allow it to top 42 mpg on the highway. Even better, Cruze Eco owners are actually averaging over 41 mpg, to the EPA's 33 mpg combined mileage.
The Cruze Eco is a good example of what can be achieved with a downsized engine and an aerodynamic body, and proves that the Volt isn't the only efficient vehicle on Chevy's fleet.
2012 Honda Civic HF
Missing out to the Cruze Eco by 1 mpg on the highway, the Civic HF matches the Chevy's 33 mpg combined rating. And just like the Cruze, owners are actually averaging a much higher figure, judging by the EPA's fueleconomy.gov website. In fact, they're getting almost 40 mpg on average.
Less sophisticated than the Civic Hybrid, the HF instead makes tweaks to the regular 1.8-liter gasoline Civic. Some aerodynamic alterations allow it to slip through the air more cleanly, and low rolling resistance tires let it roll down the road easier too. It may lack excitement to drive, but it's a good alternative choice to the hybrid,
2013 Dodge Dart Aero
The Dart is very much the new kid on the block, and manages to sneak above the 40 mpg highway limit, with a Civic HF-matching 41 mpg. To achieve this it takes a similar route to its main rival, Chevy's Cruze Eco: A 1.4-liter, 160-horsepower turbocharged gasoline engine. In this instance, it's sourced from Chrysler's partner Fiat, which uses a similar engine in Fiats and Alfa Romeos.
The engine uses Fiat's "MultiAir" technology, which uses electro-hydraulic variable valve actuation to continually alter the fuel and air mixture for best performance and economy. In addition, the Dart Aero swaps some steel components for lightweight aluminum, electric grille shutters to reduce drag, and other aero aids.
2013 Fiat 500
Rounding out our top five non-hybrids, the cute Fiat 500 is one of the better minicars when it comes to highway mileage. It just sneaks onto our list at 40 mpg thanks to 2013 model-year tweaks, and at 34 combined it's second only to the Passat TDI in this list. Rather than being packed full of fuel-saving tech, the 500 actually employs a fairly low-tech, old-school way of improving mileage--a small engine and light body.
Provided you can live with the Fiat's retro image, you'll find a lot to like elsewhere too. It's fun to drive, attracts loads of attention, and can even be had as a roll-back convertible, for the more extroverted among us...