After three years of leaving things as they were, Nissan has been doing quite a lot of tweaking to the 350Z lately. A revised model was introduced in spring 2006 boasting more power than previously, and for 2007 there have been further modifications to increase the bhp total still further.The 2006 upgrade brought the 350Z's output up from 276bhp to 296bhp, but at the expense of low- and mid-range performance. The later work, which involved replacing 80% of the original engine parts, increases the figure still further to 309bhp, as well as raising the rev limit from 7000rpm to 7500rpm, but more importantly it also means that the car is much stronger at the kind of revs most people will use most of the time.You can see the difference from outside; not because the engine itself is visible, but because it's taller and has therefore obliged the designers to modify the shape of the bonnet. Other changes include a switch from Bridgestone Potenza RE040 tyres to RE050As for improved ride quality, along with the introduction of Temper Orange, Twilight Grey and Night Blue exterior colours to replace the previous Sunset, Gun Metal Grey and Azure Blue (you can still get Solid Red, Universal Silver and Ebisu Black).Changes to the headline performance figures are minimal. The 350Z is still limited to a top speed of 155mph, and its 0-62mph time has improved by just 0.1 seconds to 5.7 seconds. Officially, the combined fuel economy remains as it was, at 24.1mpg (equating to 280g/km) of CO2 emissions, though in real life a current 350Z will probably use a bit more petrol than previous models did.The overall effect is that the 350Z is now more interesting than before in a straight line, and there's no doubt that the 3.5-litre V6 engine sounds fantastic every time you floor the throttle. But despite Nissan's claims that this is "a true, no-compromise sports car" employing lessons learned from various motorsport vehicles, the 350Z has never really been that sporty, and if anything it's less so now.In my experience, the best 350Z by a very large margin was a one-off special developed by NISMO back in 2004. It showed what could be done with the car, and perhaps just as importantly it showed what has not been done with the models offered for sale in the UK.In its current form, the 350Z is at its best under hard acceleration, or while cruising. You might expect it to be pretty good on twisty roads too, but it's not. Or, at least, not all of it is. The front end is magnificent; a light but definite turn on the steering wheel sends the nose darting into a corner without any hint that the front tyres are going to break loose.The problem is that the rear can't keep up. Early in the corner the car feels so secure that you imagine you could apply as much power as the engine could provide, but in fact even a light touch on the throttle is enough to set off the traction control.This could mean that the traction control has been programmed to come in very early, or that there really is a rear-end problem of some kind (in the form tested here, at least - the NISMO car was another matter entirely). Either way, the current 350Z is no more of a car for the enthusiastic driver than any of its production predecessors have been.There may be people who would like a 350Z but don't feel it's sporty enough for them. If so, that still leaves a lot of customers who are quite happy with the car the way it is. It's very distinctive - you wouldn't mistake it for anything else on the road - and the impressive take-up rate for the various optional extras suggests that owners quite like their comforts.Most of those extras are combined in the GT Pack, which consists of heated and powered leather sports seats, cruise control and an uprated audio system. This costs £2500, and the majority of European buyers go for it. Birdview satellite navigation adds £1200 to the cost, and Alezan orange interior trim brings the price up by another £400, so you could end up spending £30,895 on a 350Z Coupé (or £32,395 on a Roadster).If you prefer something a little less eye-catching than the Alezan orange trim there's a new alternative for 2007 called Frost, which is pale grey and is a no-cost option.Also new are the active headrests, designed to reduce the risk of neck injury in a rear-end impact, and - more trivially - an illuminated ignition switch. The 18" RAYS forged alloy wheels, Bluetooth mobile phone set-up, gearchange indicator, climate control air-conditioning, switchable electronic stability control and bi-xenon headlights of the outgoing model are all still available as standard equipment. Engine 3498cc, 6 cylinders Power 309bhp Transmission 6-speed manual Fuel/CO2 24.1mpg / 280g/km Acceleration 0-62mph: 5.7 seconds Top speed 155mph Price £26,795 Details correct at publication date