The EPA rates the 2013 GS 450h at 29 mpg city and 34 mpg highway, for a combined rating of 31 mpg. Not only is that far better than the 2011 GS hybrid's 23 mpg combined, it also trounces its closest rivals from Infiniti and BMW, which manage combined ratings of just 29 mpg and 26 mpg, respectively.
The extra economy doesn't come at the expense of performance, either. Under the hood is a 3.5-liter V-6 running lean on the Atkinson cycle, connected to a pair of motor-generators and a nickel-metal hydride battery pack in the trunk. The net output of 338 horsepower is achieved with more compact motor and battery assemblies, direct injection for the engine, and better cooling for the hybrid power system. The GS 450h can be driven on battery power alone for short distances, and can run on gasoline power alone, too.
The engine and motor combination provides enough power to cover the 0-to-60-mph sprint in about 5.6 seconds, with a top speed of about 134 mph. Some drivers may dislike the sustained high revs of the engine under hard acceleration--a characteristic of its electronic continuously variable transmission (e-CVT)--but the V-6 is a smooth, refined engine nevertheless. It emits a sporty growl at higher speeds, but remains near-silent the rest of the time--shutting off completely when coasting or running on electric power at lower speeds.
On the dynamic side, Lexus has opted to make its semi-active suspension standard on the hybrid, along with electric power steering and a drive-mode selector that alters settings in the e-CVT for Eco, Sport, Sport-Plus, and EV modes--as well as the Normal default mode. In sport-orientated F-Sport trim, the GS 450h also gets an active rear-wheel steering system, which improves turning response at lower speeds, and stability at higher velocities.
It makes the new GS feel far more dynamic than its predecessor. It's happy to tackle both twisty roads and long stretches of highway. While it falls short of being the dynamic benchmark in its class--look towards BMW for that--it should provide enough more than enough entertainment for the buyers Lexus aims at.
Joining the more aggressive exterior styling, Lexus has endowed the hybrid model with unique touches. The usual blue hybrid badges and blanked-off tailpipes are applied to the exterior; inside, the GS 450h wears unvarnished bamboo as its calling-card finish, and the hybrid's information screens dominate the dash LCD readouts.
Otherwise, the GS 450h has all the usual luxury features, and options include the same Mark Levinson audio system and Entune connectivity, with in-car apps like Pandora and Facebook.
You can find a full review of the 2013 Lexus GS 450h at The Car Connection.