Toyota's modern-day reputation for building dependable but not especially interesting cars has been jolted by the introduction of the GT86 coupé. There has been nothing like this from Toyota since the last of the Celicas, a car I enjoyed very much and missed when it was discontinued.The GT86 is, I suppose, what a two-generations-on Celica would have been. It's also less of a Toyota than any Celica ever was, and that's because it has been co-developed with Subaru, which as I'm sure you already know sells an almost identical car called the BRZ.Subaru's most obvious contribution to the project has been a 197bhp two-litre petrol engine. Its behaviour will be discussed later. For now, the important thing is not so much what it does as what shape it is.Like every Subaru engine since the reign of Henry IV, this one is "flat" in the sense that the cylinders sprout outwards from the crankshaft, rather than either upwards or diagonally as is the case with in-line or V layouts. And that's important thing because the engine is therefore very low, and so in turn is the car's centre of gravity.A low centre of gravity, like low weight, brings nothing but positives to a car. It gives the GT86 an immediate advantage and should, assuming the suspension has been set up reasonably well, almost guarantee excellent handling.The early signs are good. My first act in the test car was to drive it for two hours, at night, on deserted, flowing A-roads. Nearly everything about it was pleasing. For a start, although this is a low car and I'm an above-averagely tall person, there's a remarkably amount of interior space (at least in the front - the rear is so cramped that it was hardly worth the bother of putting seats there), and all the controls were so well-placed for me that I half wondered if my body shape had been used as the template by the designers.The seats are brilliantly supportive (though I did blink a few times when I discovered that these particular ones, heated and upholstered in leather and alcantara, are a £1600 option), the steering feel is absolutely top-notch, and although visibility is no better than you'd expect from a coupé there is no problem about seeing directly behind you because the rear window is huge.Noise levels are quite high, and ride quality isn't up to much, partly because the front suspension is under-damped and partly because the tyres - even though they're not especially low-profile and seem to have fairly soft sidewalls - transmit far more information about the road surface than you really need to know. But in this kind of driving the GT86 covers the ground very well without much effort, since you can carry a lot of speed into corners and therefore maintain a good average without much accelerating and braking.That would also explain the startling fuel economy on this part of the test. The trip computer told me I'd managed 55mpg, and although subsequent measurement suggested that it was optimistic by a couple of mpg I was still well ahead of the official extra urban consumption of 49.6. The combined figure is 39.8, and I got very close to that in the course of a week despite the kind of driving I'm going to be telling you about shortly.Until now the GT86 hadn't been perfect, but it had been so good that I was expecting great delights to be revealed when I got a chance to try it out on some of the UK's finest driving roads. Well, they weren't. I know you've probably read other reviews which hail the GT86 as being one of the finest cars to drive you can buy today, but I don't agree.I'm not wildly impressed by the engine, and that's not because its power output is substantially lower than that of many hot hatches. This may disappoint some people, but the GT86 was never meant to be about straightline performance.It's the way the engine behaves that leaves me cold, though I appreciate that some people may love it. A two-litre engine without forced induction can achieve 197bhp only through high revs, in this case 7000rpm. Maximum torque (whose relationship to power is explained in this feature) isn't available until 6400rpm.Other than on a race track, you are simply not going to be spending much time at those engine speeds, and if you go much below them the GT86 is left stranded. In sporty motoring you have to have at least 2500rpm on the clock because below that nothing you do with the throttle is going to have the slightest effect, and even when you're simply trying to get from A to B you'll probably have to drop down a gear or two (a simple matter of flicking the paddleshift in the automatic version) in situations where this would not be required if you were driving almost any other two-litre car. You even have to do this in order to continue travelling at 60mph up a slight incline.But I'd be okay even with this if the GT86 were the driving machine I expected it was going to be. It isn't, and although there may be other reasons too I think the main culprit is that front-end under-damping I mentioned earlier.Its effects becomes worse the quicker you try to go. Turn-in isn't bad, but the nose of the car rises up straight away and takes a long time to settle into the attitude it was aiming for. If you apply any throttle at all before the process is complete (assuming the engine is operating above 2500rpm, of course) you immediately get understeer - not tyre-squealing, aiming-for-the-nearest-hedge understeer, but a definite widening of the line which means you have to wrestle the steering or back off the power and try again.If you wait for exactly the right moment, the chassis will take all the power you can give it, and suddenly the GT86 feels like the car Toyota promised it would be. I can't entirely object to this lesson in well-judged use of the throttle, but it seems odd that you need the accuracy of a race driver to get anything like the best out of a none too exotic road car.I'm aware that other reviewers absolutely love the GT86, and perhaps the technique used by at least one of them - going into a corner with the brakes on and applying a bootful of throttle halfway round to kick the tail out - has a bearing on this. Well, fine, but I'd rather have higher cornering speeds and less tyre wear, thanks.It wouldn't take much to sort the GT86. Another few days' work on the suspension and you'd have something that would be both easier and better to drive. Until that happens, Toyota's coupé will continue to be, at least as far as I'm concerned, a bafflingly disappointing car. Engine 1998cc, 4 cylinders Power 197bhp Transmission 6-speed automatic Fuel/CO2 39.8mpg / 164g/km Acceleration 0-62mph: 8.2 seconds Top speed 130mph Price £26,495 Details correct at publication date