Chrysler's 300C may look like a gangsta street cruiser straight from a Los Angeles custom shop, but underneath its big, bold and slightly threatening appearance the 300C is actually a surprisingly sensible car. At entry level there are affordable three-litre V6 diesel or 3.5-litre V6 petrol models, or for those who're really out to impress and don't have to count every penny there's a 5.7-litre Hemi-powered version.This big V8 pumps out a pretty sinful 335bhp and delivers a Gatso-tickling 6.4-second 0-60 time and 155mph top speed. But despite such energetic performance, last October David Finlay was prompted to comment on these pages, "The 300C [Hemi] isn't actually a sports car, of course, though it does a good job of pretending to be one if that's what you want." Well, it would appear that the good folk at Chrysler's Street and Racing Technology division must have taken that as a challenge as the even lustier 300C SRT-8 saloon has just joined the line-up.The new SRT-8's enlarged 6.1-litre Hemi motor generates 25% more power than the 5.7-litre lump, which equates to a full 425bhp, with torque up from 387lb/ft to 420lb/ft. True, certain German über-saloons like the BMW M5, Audi S6 and Mercedes-Benz E 63 AMG all produce at least 50bhp more, but this new Chrysler is priced at a mere £39,040 - the Germans cost between £16,000 and £27,500 more.Aside from a couple of two-seater TVRs, there are few if any current models which will nudge 170mph for under £40,000, and certainly none with as many doors and comfy seats.The latest 300C's acceleration figures are no less impressive; the 5.7 Hemi manages 0-60 in 6.4 seconds while the five-speed auto SRT-8 manages the same in five seconds dead. But, as any fule kno, all-round high performance amounts to more than a simple list of numbers.To that end Chrysler has equipped its new SRT with tuned Bilstein dampers, specially tailored spring rates and suspension bushings, new front and rear suspension knuckles, larger-diameter anti-roll bars and a 13mm lower ride height. Low profile Goodyear tyres are fitted to huge 20" forged aluminium wheels, while the braking system now has enlarged ventilated discs gripped by giant four-piston Brembo calipers.With specs like that it therefore wasn't too surprising that Chrysler had the confidence to launch this model to the press on the race track, the one I attended being at Hampshire's Thruxton, the fastest circuit in the UK. I chose to familiarise myself with the car on the public road first and soon found that although this model's ride may be firmer than that of other 300Cs, it's comfortable enough and, as a bonus, it recovers from bumps and dips with greater aplomb.It also sounds decently throaty and leaves no-one nearby in any doubt that there's anything less than a seriously beefy V8 under the bonnet. My only slight grumble is that there's definitely more tyre noise on the SRT-8 and this takes the form of a sort of hollow, "boinging" sound, for want of a better word, which I don't recall on other 300Cs.Although there's obviously no shortage of power, the SRT-8 weighs in at just under two tons and this, coupled with a slightly resistant throttle action, means that it doesn't leap from its perch too energetically unless you really mean it to.There's also no escaping the fact that the 300C is also a big car and so despite all those suspension mods, and quicker rack and pinion steering, the SRT-8's steering lacks the feel, swift response and immediate turn-in of, dare I say, a proper sports car.That said, and acknowledging that very few production saloons are ideal trackday weapons, this SRT-8 is certainly no duffer. On the track it can totally belie its five-plus metre length, three-plus metre wheelbase and 1965kg. Let me put it this way: if you were driving through a downhill, right hand bend with over 100mph on the clock and the tyres squealing in protest, and then you hit a sizable bump, you'd probably expect the worst. But the SRT-8 shrugs off that kind of incident without drama.There are more than a few so-called sports cars which would have threatened the cleanliness of my underwear far more, and dozens which would have completely failed to match this big bruiser's effortless and seemingly relentless turn of speed. My only real on-track criticism concerns the suede-trimmed, 8-way power-adjustable and heated front "sports" seats which, though comfy on the road, lack the necessary lateral support for hard track driving.Of course, tearing round a track at high speed may not be your thing, so the SRT-8 also offers an impressive list of standard equipment which includes a 280 Watt, MP3-compatible, six-speaker Boston Acoustic audio system with 6-disc CD, full-screen satnav, dual-zone climate control, cruise control, an electronic vehicle info centre, load-levelling rear suspension, ESP, tyre pressure monitoring, multistage front airbags, side curtain airbags, rain-sensitive wipers, rear park assist, a large powered sunroof and more.But perhaps what matters more is this car's very substantial physical presence, its blistering performance, its cosseting interior and, not least, its bargain basement price. With just 50 per year coming to the UK you may never see a 300C SRT-8 on the street, but if you do, check out the contented grin on the driver's face. Engine 6063 cc, 8 cylinders Power 425 bhp @6000 rpm Torque 570 ib/ft @4800 rpm Transmission 5 speed auto Fuel/CO2 20.2 mpg / 330 g/km Acceleration 0-62mph: 5sec Top speed 168 mph Price From £43906.00 approx Release date 01/04/2006