TRAVERSE CITY, MI – Whenever there is a fuel-economy contest between a standard gasoline-powered vehicle and its hybrid-electric-powered twin, the HEV always should win – not barely but by a lot, in order to justify the significantly higher cost of the powertrain.

Unfortunately, that’s not always the case. All HEVs are not equal. Their real-world fuel economy is notoriously sensitive to driver inputs, ambient temperatures and road conditions.

Ward’s Associate Editor Christie Schweinsberg and I discover this on our more than 200-mile (322-km) trek to the Center for Automotive Research’s Management Briefing Seminars here this week.

We set out to test how one of the newest HEVs, the Kia Optima Hybrid, stacks up in the real world against its conventionally powered sibling.

We laid down some basic rules. We would have the same starting point and follow exactly the same route to an agreed upon end a few miles from the conference center.

Windows and sunroofs would be closed for the duration. Air-conditioning would be set at 72º F (22º C) or higher, with fans set at low. Speed would not exceed 75 mph (121 km/h).

I took the HEV, which is the mechanical twin of the ’11 Hyundai Sonata Hybrid, and planned on an easy victory.

On paper, the Optima Hybrid looks terrific: Environmental Protection Agency fuel economy is 35/40 mpg (6.7-5.9 L/100 km) city/highway, or a combined 37.5 mpg (6.3 L/100 km), which is a 41% improvement from the base Optima, with its 2.4L gasoline direct-injection engine.

And, at $26,500, the ’12 Optima Hybrid is the second-lowest-priced of similar midsize hybrid sedans, after the Sonata Hybrid.

But the standard Optima starts at a mere $19,000 and is rated at 24/34 mpg (9.8-6.9 L/100 km) city/highway. And on the right route, with the right driver, we find it capable of similar fuel economy as its hybrid sibling.

With a big advantage on the highway mileage, I thought it would be easy to just set the cruise control to 72 mph (116 km/h) on I-75 and roll to triumph, aided by a 270V lithium-polymer battery, 6-speed automatic transmission and 2.4L gasoline engine.

But halfway through the trip, with the temperature well past 90º F (32º C), I am sweating, and not just because I have the AC on low and I have slowed down so much people in minivans with kayaks strapped on top are cursing at me.

I am barely averaging 31 mpg (7.6 L/100 km) at the halfway point. Then, a fortuitous traffic jam puts me into hybrid nirvana: I am creeping along at walking speed under full electric power.

Slowly my mileage improves. Once off the expressway, my efficiency increases further as I cruise through small towns, feathering the pedal.

Meanwhile, everything that is helping me is hurting Schweinsberg in her Optima EX, with the base 2.4L 4-cyl. GDI engine and 6-speed automatic.

“That stop-and-go construction traffic just north of Bay City totally plays into your hybrid's stop/start advantage,” she says. “The construction was a bummer, coming in a flat stretch that should have put me back near or above 35 mpg.”

“I am disappointed to get just 33.9 mpg (6.9 L/100 km) on my 236-mile (380-km) journey, as I saw fuel economy as high as 35.4 mpg (6.6 L/100 km), thanks to coasting down the Zilwaukee Bridge.

But almost 34 mpg for a 3,223-lb. (1,462-kg) midsize sedan? That's impressive. I achieve what I believe is a stellar number,” Schweinsburg says.

Alas, not quite stellar enough. I knew I’d need at least 34 mpg (6.9 L/100 km) to have a chance at winning. So late in the game, I start using all the hyper-miler tricks I promised myself I wouldn’t do.

If I could have figured out how to remove the floor and use my feet like Fred Flintstone, I would have. Instead, I feather the pedal and literally coast into town the last few miles.

I apologize to the patient folks in the white Prius behind me.

As I quietly roll up to the destination, 34.5 mpg (6.8 L/100 km) is showing on the trip computer. I am a long way from 40 mpg, but 0.6 mpg (0.2 km/L) ahead of Schweinsberg.

It is a hollow victory. All that expensive hybrid technology and effort on my part, and all I can do is win by a nose. For the record, the sticker price of the Optima Hybrid as tested is $32,250, while the standard Optima EX is $27,440.

“That just goes to show a hybrid, and the premium typically paid when buying one, is not always worth it,” Schweinsberg says.

That’s one way of looking at it. But how does driving an HEV affect your mood? Does it make you feel like a better person?

After driving to Traverse City in an $88,000 Cadillac Escalade Platinum Hybrid, Associate Editor James Amend finds driving a hybrid is its own psychological reward.

“After a 4-hour ride to MBS loaded with kids and a week's worth of supplies, we can confidently report few vehicles strike a better balance between family friendly and environmentally friendly,” Amend says.

And don't fret about giving up fullsize-truck capability. The Escalade Hybrid still packs 332 hp and 367 lb.-ft. (498 Nm) of torque. The hybrid compromises a whisker of towing capability but probably nothing most people would miss.

Only the Brady Bunch would need more cargo space, Amend says.

“The Escalade Platinum Hybrid scores 15.5 mpg (15.2 L/100 km) plucking around metro Detroit and 18.5 mpg (12.7 L/km) on the highway. The highway miles include about 30 minutes of maddening 1-lane stop-and-go travel, where we creep along stealthily using just the battery.”

The Environmental Protection Agency rates the vehicle at 20/23 mpg (11.7-10.2 L/100 km).

“It would be a stretch to call the Escalade Platinum 2-Mode Hybrid a fuel sipper,” Amend says. “But consider a traditionally powered model with a 6.2L V-8 is rated at 13/18 mpg (18.1-13.1 L/100 km) city/highway, and it starts making some sense.”

Well, sort of.