This fuel economy fad looks like it might actually catch on. In the year in which global sales of Toyota hybrids surpassed 4 million, production of high-mileage alternative-fuel vehicles is accelerating.

As the company that pioneered hybrid-powered cars, Toyota sells 18 hybrid passenger vehicles in 80 countries and regions around the world. Fifteen years after the Prius went on sale in Japan, hybrid vehicles account for 15 percent of Toyota's global sales. Prius, Toyota's first hybrid passenger car, went on sale in the United States in 2000.

Since then, the Toyota Motor Sales U.S.A. has sold 1.5 million hybrid vehicles in the United States, accounting for 65 percent of all hybrid vehicles sold in the region. Prius, the iconic hybrid brand, makes up half of all hybrids on the road in the United States, with sales totaling 1.2 million units through April 2012.

The Prius v was introduced in to the market in November 2011, followed by Prius c and Prius Plug-in during the first quarter of 2012. Toyota's other U.S. hybrid models include versions of the Camry and Highlander.

But Toyota now has a lot of company in hybrid and electric-powered vehicles.

The Chevrolet Volt, a Detroit-built car that won acclaim as the first "plug-in hybrid," is carrying updates for 2013 that include a coveted "green sticker" for single-occupancy high-occupancy vehicle lane access in California and New York.

Volt also adds a "Hold mode" that allows owners to direct when the Volt uses its gas generator. This feature helps save money because owners who mix city and highway driving can save the battery charge for city travel, where the Volt's EV mode operates most efficiently.

Ford Motor Co. is adding competitive pressure with the Ford C-Max Hybrid, which is officially EPA-certified at 47 miles per gallon. Ford claims its 47 mpg beats the Toyota Prius v by up to 7 mpg.

"We've done this with innovation -- represented by nearly 500 hybrid patents -- while driving costs down 30 percent so we can bring these fuel-saving vehicles to more customers," said Ford Vice President of Powertrain Engineering Joe Bakaj.

Ford is pitching the C-Max Hybrid as America's most affordable hybrid utility vehicle with a base price of $25,995.

In its first full month of sales for the 2013 model year, C-Max Hybrid led Ford to its best October hybrid sales month with a total of 4,612 sales, up 142 percent over October 2011.

The C-Max Hybrid will offer a top speed of 62 miles per hour in electric vehicle mode and 188 net horsepower, according to Ford. When powered by gasoline, the C-Max Hybrid uses a new 2-liter Atkinson-cycle four-cylinder turbo-charged engine.

Ford is also selling its own plug-in hybrid version known as the C-Max Energi.

The C-Max Energi achieves up to 21 miles in all-electric range -- more than triple Toyota Prius plug-in hybrid's 6-mile all-electric range.

"The C-MAX Energi is the most affordable, most fuel-efficient plug-in hybrid with the longest overall range for any utility or compact vehicle on the market today," said Michael O'Brien, Ford electrified vehicle marketing manager.