I have a theory . . . no, hang on, this is quite a good one . . . about high-performance versions of a given range of cars. Right up at the top there will be a really spectacular model, the one with lots of grunt, which grabs all the headlines and is the one the racier customers aspire to.A level or two below that there will be something that still looks good but is only pretending to be as fast as the fancy one. It won't be as quick but it will be a good deal cheaper, more economical and not as expensive to insure. And it will frequently be a better car than the one at the top of the range, or at the very least a better car than the lesser specification would suggest.So, about the Renault Clio Si. It has 1.4 litres (not that much for a car of this size, given that there were two-litre Clios several years ago) and 98bhp. Not exactly a tarmac-scorcher, then, or so you might think. But it's actually a very respectable sporty hatchback.That 98bhp figure might lead you to think of the Si as being pretty arthritic, but if there really are only that many horses, as racing drivers are apt to comment wryly if they hear a rival quoting a suspiciously low power output, they're certainly all pulling in the same direction.Low gearing has a lot to do with this - you get little more than 20mph out of every thousand revs in top gear. But the Si engine also works very well at low to medium revs, so there's a useful surge of acceleration even if you only tickle the throttle.I took the Clio over a favourite ten-mile section of twists and yumps (the sort of thing that would make a fabulous special stage on a closed-road rally) and went quite as fast as I wanted to despite hardly ever putting the throttle to the floor.The handling is pretty sharp, too. You'd have to be doing something pretty daft to make this car understeer, because that's a trait that has been painstakingly dialled out by the chassis people.I have a slight reservation about this, though. The second best way of reducing a front-wheel drive car's tendency to understeer (assuming the best way - making the front end grip better - isn't possible for practical reasons) is to loosen up the rear. Renault has done this by making the back end both high and stiff. Each of these characteristics increases weight transfer and helps the tail of the car follow the front round corners. And it works.It also has a strange effect on the ride, which is fairly compliant at the front but very choppy at the rear. More importantly, though, it makes the Clio unstable under heavy braking in a straight line, and under quite light braking if you happen to be in a corner (yes, yes, ideally you shouldn't brake on corners, but the situation sometimes arises).In an emergency situation I can imagine many drivers losing control of the Clio altogether and spinning into the scenery. Furthermore, having once rolled at alarmingly high speed after making a big girl's blouse of Copse corner at Silverstone while driving a racing hatchback with extremely stiff rear suspension, I can also imagine a Clio Si landing on its roof if things really get out of hand and the driver panics or doesn't know what to do next.Rear-seat passengers don't have much room in the Clio (can't be much fun back there, what with the cramped surroundings and the pogo-stick ride) but there's a lot of space up front. I extend to over a fathom and didn't have any problem with headroom, which is far from being the case in many rival products.Not too sure about the driving position, though. My best compromise involved being too close to the pedals (so I couldn't brake or change gear comfortably) while at the same time being too far from the steering wheel (so I couldn't steer comfortably either). Italian cars used to be designed this way as a matter of course, and I'm not sure why Renault has now started to do likewise.It's a shame, because I enjoyed buzzing around in the Si, and I would have enjoyed it far more if I had been able to operate the controls more easily.To sum up, then, a smart little sports model with an excellent engine and good handling. But you have to be the right shape, not mind about the ride quality too much, and - most important of all - have your wits about you if you get the car even slightly out of shape.Second opinion: Isn't the idea not to get the car out of shape, slightly or otherwise? The Si is hardly meant to be the chuck-about Clio, and the people who usually buy a car like this aren't likely to be into chassis engineering. It's a mildly sporting car in a low insurance group, although I enjoyed out-handling a couple of Lagunas on another winding B-class road with plenty of brows and blind corners. The Si has a very nicely designed front cabin, and I can see why it attracts so many women customers. But I always think the front end is a poor match for the rear "architecture". Ross Finlay. Engine 1390cc, 4 cylinders Power 98bhp Transmission 5-speed manual Fuel 43.5mpg Acceleration 0-62mph: 10.5 seconds Top speed 116mph Price £10,895 Details correct at publication date