I've moved from a BMW 730 to a GS 450h. Being dissillusioned with the current 5-series, and not wanting to continue driving a barge, it was going to be a high-spec 3-series, or a GS 450h. I suppose it's inevitable I will tend to make comparisons to the BMW, so please don't be offended by that.
This car isn't going to save the planet, and I don't think fuel economy would be the main reason for buying one. My 730 returned between 23-26 mpg, and so far the GS isn't that much better. To be fair, I am driving the GS slightly more enthusiatically than I did the 730, but even with a lighter foot, I'd consider I was doing well to acheive 30mpg. What I do know is the GS is making every effort to make the best of the fuel available, and it would probably be worse if it wasn't doing that. I can now accelerate without feeling I'm sucking the tank dry every time I do.
The GS has a harder ride than many cars in its class. I wish it didn't have low profile tyres because they don't help. But it is solid on the road, and despite its weight, drives like a smaller car. Acceleration is breathtaking. But more than that, it's the way it is delivered that impresses. There are no obvious gear changes. You put your foot down, and there is a humming noise, seemingly unrelated to the car speed, and the car accelerates forward gracefully without any fuss. There is no aggressive engine noise, and it all seems so effortless. Pulling out of a sideroad to join a fast-moving stream of cars is so easy. You can join in gaps you simply wouldn't consider in a lesser car.
Problems so far revolve around the parking brake. If there's one thing Lexus could do to make this car almost perfect, it would be to use a normal handbrake, or better still an auto-hold parking brake. When arriving at a T-junction to join a main road, the car will stop, and the engine stops with it. But if you're on a hill, and heading upward, the car will then roll back. I suppose I'm used to driving BMWs that simply won't let that happen. You can't go backwards in a BMW if you're in Drive. In the GS, you need to keep your foot on the brake, and then change to accelerator when you set off. This isn't the most elegant way to control a car on a hill.
The GS corners very well. I'm sure IS owners are going to say they prefer the smaller, lighter car. But the GS is what it is, a mid-ranged saloon car. It doesn't have the "throw it anywhere, it'll be OK" feel of the BMWs, but it is a safe ride, with a good feel to the steering. If you feel you need to brake heavily into corners, the 450h gives you back that energy as you come out of the corner, and it's quickly back up to speed. It's almost fun to drive.
Little niggles. The voice recogniition is not one of the best. The BMW would politely ask you if it couldn't understand. The GS seems to go with the nearest fit and gets it wrong most of the time. If it's not sure, it should ask, not guess. The satnav map always seems too close in, and it's not easy to change the scale. I'm sure there is a way, but I can't find it.
I don't want anyone to think I'm criticising this car. I'm not. It's a great car and very different to anything else on the road. I will miss my BMWs, but I am happy to join the Lexus clan, and look forward to getting to know you all.