Now in its 14th year, the Ward’s 10 Best Engines list recognizes not only great powertrains but those who create them.

Powertrain engineers often toil in obscurity, getting their hands dirty in the often thankless task of building components that will be cut from solid chunks of metal and then pieced together on the assembly line.

If all goes according to plan, the finished product achieves internal-combustion harmonic balance – and lures new customers to a particular vehicle or brand.

A mediocre effort leads to middling performance, recalls and disgruntled consumers that can send a company into a tailspin. A truly bad engine can tarnish an auto maker’s reputation for a generation.

No auto maker wants such a fate, so the power, quality and reliability of today’s engines are constantly improving.

That’s what makes selecting the best engines every year such an intimidating and difficult challenge for Ward’s editors. Yes, some of the least engaging entries easily are bumped from contention.

But every year, we test a superb lot of powertrains that dazzle and beguile us. Reaching agreement on the final 10 is a bruising, draining and exasperating process.

Not to mention thrilling, educational and fun. For those of us with gasoline in our veins, the 10 Best Engines is better than the 12 days of Christmas.

This year, we tested 37 engines, with six editors experiencing each vehicle in their routine, daily driving cycles. The 37 nominated engines include the 10 winners from 2007, plus all new or heavily revised engines for ’08.

All regular-production test vehicles must be available in U.S. showrooms during the first quarter of 2008 and must have a base price not exceeding $54,000.

There are no segments in our evaluations for cars or trucks or 4-cyl. engines or V-8s. Each stands on its own, and the editors score each engine based on how they perceive that engine competing against others like it. Points are awarded based on several criteria, including technology, power, refinement and fuel economy.

This year’s list is broadly indicative of the type of engines U.S. consumers prefer: Six are of the 6-cyl. variety, while two are V-8s and two are I-4s – the same mix as 2007’s 10 Best Engines. Direct injection is employed by six of the winning engines this year, reflecting the trend toward smaller engines with more power.

And for the third time since the Toyota Prius made the list in 2001, a hybrid-electric vehicle earned a spot – this time the GMC Yukon Hybrid, equipped with General Motors Corp.’s jointly developed 2-Mode HEV architecture.

Likewise, each year a hybrid has made the list, so has a new-generation turbodiesel. This year’s winning oil-burner is the Mercedes E320 Bluetec, which also earned an award last year. The arrival of several new diesels for the U.S. in 2008 will make for an exciting competition next fall.

And the new federal mandate for U.S. light vehicles to achieve 35 mpg (6.7 L/100 km) by 2020 surely will produce some fascinating new concepts to evaluate for 10 Best Engines in the coming years.

That’s because behind every great engine is a team of dedicated engineers and smart management willing to focus their energies on even the most daunting tasks.

tmurphy@wardsauto.com

Ward’s 10 Best Engines is copyright Penton Media Inc. Commercial references to the program and/or awards are prohibited without prior permission of Ward’s Automotive Group.