Of the dozens of 2011 vehicles I’ve tested, two of the most impressive new models were a pair of midsize sedans, the Buick Regal and Kia Optima.

I wrote plenty of nice things about both vehicles, but one thing also disappointed me about the two test cars: Neither was turbocharged.

Kia and Buick both addressed that recently by sending me, respectively, an Optima SX and a Regal CXL Turbo. That gave me an excuse to revisit both terrific vehicles.

Before I get to the cars, let’s talk a bit about turbocharging. The technology was so popular several years ago that it took on an almost magical aura. “Turbo” became a prefix used for marketing just about everything from Internet service to razor blades.

I don’t recall anybody selling turbo baby diapers, but it wouldn’t have surprised me. Not surprising is that most of the turbo references were a bunch of baloney. But there’s nothing bogus about the benefits of real turbocharging, which has been used for decades to prod more power from internal combustion engines.

In simplest terms, a turbocharger uses an engine’s exhaust gas to spin a pair of turbine fans, one of which sucks in fresh air, compresses it, and then feeds it to the engine’s air intake system.

Because engines produce power by mixing air and fuel, the more air an engine can gulp the more power it is capable of producing. It’s not unlike fanning the charcoal on a grill to produce more heat.

Turbocharging is one of the most efficient methods of boosting an internal combustion engine’s power. Automakers like to say that turbocharging delivers six-cylinder power with four-cylinder fuel economy.

That isn’t much of an exaggeration if you look at the performance of the Regal CXL and Optima SX turbo models. Both are powered by 2.0-liter, four-cylinder engines, which are nearly 20 percent smaller in displacement than their respective 2.4-liter, non-turbocharged, base engines.

Despite being significantly smaller than its normally aspirated counterpart, the Optima’s turbo engine produces 74 more horsepower (274 vs. 200) and 83 more pounds-feet of torque (269 vs. 186).

It’s a similar story with the Regal. Its turbocharged engine delivers 38 more horsepower and 86 more pounds feet of torque than the Regal’s larger, non-turbo standard engine.

Anyone paying attention might wonder why the Optima’s turbocharging produces significantly more power than Buick from the same size engine. The answer is that Kia uses a trick new turbo design developed by Hyundai. You can read more about it at this forum:www.optimaforums.com/forum/5-optima-general-discussion/302-turbo-release-date/html.

According to my stopwatch, turbocharging enables the Regal to trim 1.1 second off its zero-to-60 time. The more powerful Optima fares even better, improving its 0-60 sprint time by 1.6 seconds.

Both the Buick and Kia turbocharged engines provide their power boosts without sacrificing much fuel economy.

According to the EPA ratings, the Regal turbo gets 18 city/28 highway mpg versus the non-turbo Regal’s 19/30 rating. The Optima turbo’s 22 city/34 highway mpg comes even closer to matching the non-turbo’s 24/34 rating.

The Kia gets better mileage in part because it weighs 215 pounds less than the Buick. Since it weighs more and has less power, it’s no surprise that the Regal takes about a second longer than the Optima to go from zero to 60 mph.

But this isn’t a comparison test because despite both being midsize sedans, Buick’s Regal and Kia’s Optima are aimed at different audiences. Buick positions the Regal as a near-luxury car competing against the Acura TL and Volvo S60. Kia’s targets are more mainstream midsize models such as the Honda Accord and Toyota Camry.

Turbocharging makes both models very competitive.

I already loved the Regal’s refinement and German-bred road manners. The turbo model doesn’t add a lot of standard features or awe-inspiring power, but its extra oomph makes it an even stronger contender in its class.

And the Optima SX Turbo, which gets a bunch of feature upgrades in addition to significantly more power, might have moved right to the head of its class.

In summary, let’s just say that in the case of these cars the “turbo” prefix really does signify a boost in performance and desirability.

Scott Wasser is executive editor of MaineToday Media. He writes a weekly auto column for the Sunday Telegram and other newspapers. He can be reached at

swasser@pressherald.com.