With either the 303-horsepower, 3.5-liter V-6 in the 2010 Lexus GS 350 or the 342-hp, 4.6-liter V-8 engine in the GS 460, these sedans move authoritatively; the Lexus GS 460 models can reach 60 mph in only 5.4 seconds, according to Lexus' usually conservative numbers. Cars.com says, "[GS] 350 buyers aren't likely to find the V-6 wanting for power," while ConsumerGuide attests that the Lexus GS 460's "4.6-liter V8 engine gives GS 460 lots of go."
The 350 gets a six-speed automatic, while the 460 boasts eight speeds; in either case, the transmission has a silky, unobtrusive demeanor in normal driving, but paddle-shifters allow you to manually access all those ratios. ConsumerGuide observes that the eight-speed automatic transmission "changes gears frequently, but [is] smooth overall and a good match to the engine." Six-cylinder models make do with the six-speed automatic.
The 2010 Lexus GS 450h has a full-hybrid powertrain pairing a 292-horsepower, 3.5-liter V-6 with an electric motor system, propelling the rear wheels and charging its battery pack when coasting and braking. Altogether, the hybrid powertrain makes 339 horsepower and can push the 450h to 60 mph in just 5.2 seconds—faster than the V-8-powered GS 460. The GS 350 is additionally available in an all-wheel-drive version.
ConsumerGuide notes that the "hybrid powertrain lacks immediate kick of V8, but does surge ahead with dispatch," an impression confirmed by Car and Driver: "when all the ponies and volts are online, the 450h is capable of respectable haste." According to Cars.com, the "direct-injection, 3.5-liter V-6 engine is shared with Lexus' smaller IS 350 sedan," which teams up "with two electric motors—one providing power during startup, the other boosting acceleration—for a combined 339 hp."
Nevertheless, reviewers had plenty of positive comments about the hybrid powertrain’s performance. Autoblog reports that the GS 450h is "tuned for even more performance and has the rear-wheel drive to handle it." Automobile Magazine points out "gasoline and electric propulsion units really do work as a single entity."
The Lexus 450h has, instead of a conventional automatic transmission, a continuously variable unit. Automobile notes that "the continuously variable transmission acts more like a standard automatic in its engine-braking abilities—just slide the lever over into 'S' and toggle down through six 'gears.'" This source adds that the "faux downshifting doesn't help with acceleration, but the GS doesn't need it." Car and Driver doesn’t like it, complaining that "the continuously variable transmission never stopped hunting."
People will likely select the hybrid for its greener reputation, and the promise of significantly higher fuel economy, but TheCarConnection.com hasn’t managed to achieve the 450h’s EPA ratings of 22 mpg city, 25 highway in real-world driving. As such, it’s not much better than the GS 350’s EPA figures of 19/27 mpg.
Whichever way you have them, the GS sedans handle well, with impressive stability even over rough surfaces, thanks to a double-wishbone front suspension and multilink rear setup. The electric-assist power steering is well weighted, but the lack of road feel could be an issue for hard-core sport-sedan aficionados.
Each of the 2010 Lexus GS sedans offer "various supplemental handling assists," according to Kelley Blue Book, most of which can "be switched off completely by anyone who really does want to press to the edge of the envelope." One of these is "electronically-boosted variable power steering," which they say is "both quick and precise." Cars.com reports that the steering system actually "changes the steering ratio for tighter or wider steering depending on the speed of the car." ConsumerGuide acknowledges that "cornering lean is modest, and grip and balance are both good," but while "stopping control is strong...to some testers, the pedal action is either too mushy or too sensitive." Other options include an Adaptive Variable Suspension (AVS) system, which gets four different firmness settings.
ConsumerGuide notes that the 450h is "comfortably unruffled on smooth pavement" but points out "minor float over large humps." On the 450h, Car and Driver complains of "numb steering," adding that "the total absence of feel in the electric power steering reminded one tester of an early-'80s Lincoln Town Car."
Brakes provide "strong stopping control, but...pedal action is either too mushy or too sensitive," according to ConsumerGuide. Edmunds also complains of a touchy brake-pedal feel, adding that it’s “quickly taken in stride, however, and the regenerative braking system otherwise stops the 2-ton GS 450h quickly and with reassuring authority."