In 2013, total sales of electric and hybrid vehicles skyrocketed by 223 percent. Hybrids now make up three percent of the American auto market, and the man to thank is Nicolas Léonard Sadi Carnot.

In 1824, Carnot proposed an eponymous theoretical thermodynamic cycle that proved, once and for all, that no heat engine can be 100 percent efficient. In fact, the maximum theoretical efficiency of most gasoline engines is about 45 percent. Real-world values hover around 35 percent. In other words, when you pay $4.00 for a gallon of fuel, $2.60 never makes it through the exhaust pipe.

Contrast that with a new brushless DC motor developed at Tokai University, Japan, which boasts conversion efficiency of 96 percent.

Waste not, want not.

What Is a Hybrid Vehicle?

A hybrid vehicle marries the power and versatility of an internal combustion engine with the efficiency and cleanliness of an electric motor. Hybrids come in two basic flavors:

• Parallel: Where the electric motor can power the car, the gasoline engine can power the car, or the duo can work together.
• Series: Where the gasoline engine charges the battery that feeds the electric motor.

The Nerd’s Take: Hybrid Technology

A thorough mechanical discussion of hybrid powertrains would dive into planetary gear sets, total harmonic distortion, lithium-ion atomic bond energy and other legerdemain. But leave all that to the engineers. The point to take away is that hybrid powertrains either A) exploit the inherent conversion efficiency of an electric motor and/or B) allow an internal combustion engine to run in its most efficient rpm range.

Many hybrid SUVs also come with low rolling-resistance tires, shutter grille vents, aerodynamic drag fins and other ancillary technologies to help improve fuel economy.

A Synopsis of the Hybrid SUVs Market

Rewind by one decade. Only four hybrid models were sold in America. Today, there are dozens. Popular hybrid SUVs include:

Audi Q5 Hybrid: With a potent 245-horsepower engine, all-wheel drive and 30 highway mpg, what’s not to love? Its main contender is the Infiniti QX60 Hybrid.

Subaru XV Crosstrek Hybrid: What could possibly beat standard all-wheel drive, 8.7 inches of ground clearance and 31 combined mpg? Rugged competitors include the Nissan Pathfinder Hybrid and the Toyota Highlander Hybrid.

Porsche Cayenne S Hybrid: For those who can’t abide compromise, the Porsche Cayenne S Hybrid comes with a 151-mph top speed, eight-speed automatic transmission and more optional features than a Build-a-Bear store.

Lexus 450h: The long-loved hybrid SUV from Lexus boasts pre-collision safety systems, cabin voice commands, smartphone app integration and beautiful wood trim accents. Competitors include the Volkswagen Touareg Hybrid.

Differences of Driving a Hybrid SUV

Hybrid vehicles offer similar range, speeds and maneuverability to gasoline-powered cars. However, they boast more low-end torque, reduced emissions and a quieter driving experience.

Benefits of Hybrid Cars

Hybrid SUVs help save rainforest acai palms, rescue Arctic polar bears, decrease city smog emissions, reduce dependence on foreign oil, etc. Hopefully those reasons are good enough, but if not, consider the math:

• Payback period. As fuel costs increase, payback periods decrease. The current payback period for many hybrid SUV’s is 8-9 years, which can be recuperated during a single period ownership.
• Insurance discounts. Insurance companies often hand out instant discounts for owning hybrid SUVs.
• Tax incentives. Incentives vary by state but can reach into the thousands of dollars.

But again: Waste not.