The hybrid-drive Toyota Prius is a bit like the result of an explosion in a good ideas factory, which is a significant intellectual element in its appeal to potential buyers. Rather than repeating the full specification here, though, I'll simply refer you to our recent launch review and concentrate on what it's like to live with a Prius - in this case the mid-range T4 version.This is, of course, the second-generation model. The original Prius, which we tested back in September 2001, was quite brilliant, but in many (though not all) ways the new one is significantly better.It's certainly a lot more attractive. This still isn't the most elegant-looking car on the market, with that large area of metal between the rear wheels and the windows, but it no longer qualifies for the adjective "frumpy".Although it's really a hatchback, the Prius has a certain MPV element to it. This occurs in both good and bad ways, the bad one being the fact that the A-pillars are so enormous that Toyota has had to cut little windows in to them to help visibility at road junctions.The good way concerns the interior space. There is a quite colossal amount of this, not only in the front (which is the easy bit) but also in the rear. I can't immediately to bring to mind any other sub-£20,000 car that allows four adults to sit quite so far apart from each other. The only limitation is that the sloping roofline intrudes slightly on the rear headroom, and can cause problems for passengers whose height extends beyond six feet, but otherwise this is an extraordinary piece of packaging.Luggage room isn't so good because the boot area has quite a high floor. This floor is partly false, and a section of it can be removed to create an extra few inches of depth, but if you do that you're left with a most unusual luggage compartment shape and are forced to put some of your clobber on top of the tools. That could become messy if you've recently had to change a wheel.Driving the Prius is a slightly unusual experience. The 1.5-litre petrol engine is pretty quiet, but you are still aware of when it shuts down, which it frequently does if the supplementary electric motor is able to provide enough power for whatever you are doing (you can also see this happening if you choose the appropriate setting on the central display monitor). Onlookers gaze in astonishment as you manoeuvre silently in car parks, and it's possible to feel very smug indeed as you sit in a traffic queue with the engine at rest while everyone around you is using up fuel to no good purpose.As we've explained previously, the electric motor also gives extra power when the engine is running (leading to performance which is useful without being startling), and the battery pack which runs it is recharged every time the car slows down - or indeed when you lift off the throttle to maintain a constant speed downhill.One passenger assumed that all this technology must make the Prius quite difficult to drive. Not at all. Everything is controlled automatically. That principle extends to the continuously variable transmission, which as with all units of its type simply requires you to decide whether you want to go forwards or backwards, and takes care of all other gearing decisions itself. All you have to do is accelerate, brake and steer.Steering isn't in fact quite as easy as it might be, because the wheel is not adjustable for reach (though it is for height). For me, it's too far away, and I had to extend my arms more than I normally like to, which was tiresome on long journeys. The quality of the steering itself, though, is excellent.Not so the ride. Odd, this. I reckoned the old Prius had by far the best ride quality of all the dozens of cars I drove in 2001. The new model is fine on smooth roads but to me (though not to all my colleagues) it feels very cumbersome as soon as you have to deal with bumps and crests - understandable when you consider that it has an electric motor and battery pack to carry along with the engine and transmission, but less so given that the older version had exactly the same. Prius II is also very susceptible to sidewinds, as I found during blustery conditions over a couple of days.Toyota says it has set up the UK model Prius for sporty driving compared with the American and Japanese equivalents, but let's not get too excited about that. You wouldn't take it out for a sprint across country roads just for fun.The really big deal with the Prius is the high fuel economy and almost unbelievably low CO2 emissions figure. In the days of the old Prius there was some journalistic concern that the car wasn't really any more economical than a decent turbo diesel, but during this test I found no problem at all in achieving an average of more than 50mpg. No turbo diesel of comparable size that has recently come through our hands would have been able to manage this without very careful attention to economical driving.But there is more to the Prius than its fuel usage and its general cleverness. The ease of driving and the huge interior space are every bit as appealing, while the ride quality and lack of that last inch of rear headroom are relatively minor points. It's a splendid piece of work, definitely worth considering if you're looking for a practical family car.