2010 Lexus HS 250h

This all-new HS 250h is far from Lexus’ first hybrid. Toyota’s luxury brand says it has sold some 170,000 GS 450h, RX 400h, RX 450h and LS 600h L hybrids in the last few years. But those are gas/electric hybrid versions of conventional vehicles. What Lexus has not offered until now is a “dedicated” hybrid-only model comparable to parent Toyota’s popular Prius.


Although sharing the new 2010 Prius’ dedicated hybrid architecture would have spread its high cost between the two cars and brands, Lexus says this new HS 250h hybrid sedan shares virtually nothing with the hatchback Prius except its Synergy Drive hybrid propulsion system. It is a somewhat larger car—longer and wider on a longer 106.3-inch wheelbase—and packs a larger, more powerful 147-hp 2.4-liter 4-cylinder engine vs. Prius’ 98-hp 1.8-liter four.

Hybrid System

This high-efficiency Atkinson-cycle engine is Lexus’ first four-cylinder. It features four valves per cylinder, a relatively high 12.5:1 compression ratio and Variable Valve Timing “with Intelligence” (VVT-i) on the intake side, and it employs an exhaust heat recovery system that speeds warm-up, allowing the engine to shut down earlier and more often when it’s not needed. It also meets California SULEV and federal Tier 2 Bin 3 ultra-low emission standards. Total rated output is 187 hp (not the sum of the engine’s 147 hp and the electric drive motor’s 141-hp peak capability, since both can’t be maximized in the same operating range). Power is transmitted to the front wheels by a compact electronically-controlled continuously variable transmission (CVT), while a second electric motor serves as both engine starter and battery pack generator.


A cockpit switch offers four drive modes: “Normal” gives near-linear throttle action for naturally progressive power. “Eco” reduces throttle actuation relative to accelerator pedal angle to emphasize fuel economy. “Power” offers a more responsive feel, while “EV” allows driving on the electric motor only for short distances under optimum conditions.

Aero Shape, Mileage Yield

Hard wind-tunnel work resulted in a low 0.27 coefficient of drag (Cd), a substantial contribution to fuel economy at highway speeds. The silhouette is a smooth flowing line front to rear, and the grille has no openings to facilitate airflow over the hood. An air inlet below it and a larger one lower in the fascia provide cooling air for the hybrid system. The high-voltage battery pack, auxiliary battery and related devices are tightly packaged for a relatively roomy cabin and usable trunk space.


The HS 250h is EPA-rated at 35 mpg city, 34 highway and 35 combined—more than 20-percent better than the next most fuel-efficient Lexus—on regular unleaded gas. Our initial test drive on urban and rural roads yielded 33 mpg in Normal mode, but feather-footed drivers will be able to substantially improve on that.

Features and Options

Leather-trimmed power seats (10-way driver, eight-way front passenger) are standard. The dual-temperature climate system has a rear blower, an air filter, a pollen removal mode and a plasma cluster ion generator (?) to purify cabin air. Comprehensive noise reduction measures make the cabin eerily quiet in most conditions.


A multi-information display offers fuel economy, ambient temperature, range and more, and an optional Heads-Up Display (HUD) projects vehicle speed and other information on the windshield in front of the driver. In addition to the rear-view camera that comes with navigation, an available Wide-View Front Monitor enhances visibility around the front of the car.