Detroit: Lexus HS 250h Hybrid Concept: Should be in production by summer

The exterior styling of the new HS 250h Concept is pure Lexus; understated, if not a little vanilla. The front grill is a giveaway this car is a sister of the new RX 450h we recently took for a first drive. Maybe the design is not sassy, and definitely not brash, arrogant or 'fashion forward.' But then stop and consider the engineering marvel of a .27 drag coefficient brought about by the standard front spoiler, a rear under-spoiler, under-trays and diffuser fins. That's not quite as low as the Prius, but remember, we are talking about a 5-seat sedan. Not bad at all.

Lengthwise, the HS is a little longer than the IS, and about the same width. An area where you may notice the biggest difference is the height. The HS is taller than both the IS and ES. Again of course, that's all by design to bring about the best in efficiency.

While the HS is the fourth hybrid for the Lexus nameplate, it is the first dedicated hybrid and will not be sold with any other powertrain. Lexus says EPA tests are not finalized, but preliminary numbers indicate city mpg should be higher than the two-passenger Smart micro car.

Read between the lines: Suffering will not be a pre-requisite for buyers committed to fuel efficiency. The engine can run on regular-grade 87 octane gas.

How do they do it? First, of course, is the aero-efficient exterior. The car is equipped with a 2.4-liter engine that uses sophisticated valve timing to increase efficiency. And like the new RX hybrid, the HS has an exhaust-heat recovery system.

To add to the 'Green' appeal, 30 percent of the interior appointments are made of eco-plastics - plant-based plastics in the upholstery and luggage trim and the trunk panels.

Pure performance nuts may be turned off by the front wheel drive and the fact that Lexus says this will be a super-quiet car because they used special finishes and treatments to dampen road and engine noise. Macpherson struts are upfront with a double wishbone independent rear suspension that should help give this car a much more dignified ride than the Prius. What I mean by that is you won't worry about losing the fillings in your teeth if you hit a pothole or cross a railroad track at speed.

For a car in this luxury bracket, all the little perks are included like a pre-collision alert system, blind spot camera monitors and a class-leading ten airbags.

The car will be available this summer. Worth a test drive? Absolutely, especially if you own an older Prius and are tired of riding around in a rattle-box and want more comfort and TLC.