Used car buying guide: Mini Cooper S

But it also gained mods that looked suspiciously like a ‘fix’ to an unacknowledged problem. Changes included redesigned pistons, an uprated boost line to the turbo, improved crankcase ventilation, a heat shield over the turbo oil pipe and a rigid instead of flexible turbo intake pipe. Experts reckon the N18 is the engine to have. You can identify it by its large plastic cover, while the N14 is ‘naked’. Meanwhile, onthe transmission front, the manual gearbox gained an improved clutch for better gear synchronisation.

Bizarrely, the changes were followed a few months later by a full facelift (new bumpers, revised interior, LED tail-lights with pulsating brake lights to indicate the force being applied and additional air intakes). As already noted, in 2011 a revised timing chain tensioner was fitted. Now, at last, the R56 couldn’t spring any more surprises except the one common to any well-bought R56 Cooper S, and that’s just how much fun it is to drive.

How to get one in your garage: 

An expert’s view, Alex Castle, MASTERDRIVER.CO.UK: “The R56 timing chain can let go at around 80,000 miles. The plastic tensioner guide is the culprit. If you hear a brushing sound, it’s on the way out and you should change it without delay. The later N18 engine is much improved but the tensioner wasn’t upgraded until 2011. Fortunately, owners are enthusiastic and look after their cars. There are plenty to choose from so you can afford to be fussy. New, options were pricey, but that cost evaporates as the cars get older so fully loaded Coopers aren’t much more expensive. My favourite extras are the panoramic roof and Harman Kardon sound system.”

Buyer beware...

TIMING CHAIN - The timing chain, or more specifically the tensioner, is the weak spot. Keeping the oil topped up is vital but ultimately poor design is to blame. A rattle and brushing noises at idle from cold is the tensioner’s ‘death rattle’.

OIL LEAKS AND MISFIRES - Oil leaks are becoming an issue on older cars. Check the rocker cover, crank seals, sump, turbo oil feed, front and rear main bearing seals, solenoids and cylinder heads for drips. Valve stem seals are starting to fail on older cars. Permanently low oil allows sludge to build up in the Vanos valve control system, affecting performance. Hesitation, uneven idling and misfiring could be carbon build-up on inlet valves or failing coil packs.

COOLANT SYSTEM - Look for cracks on the plastic coolant thermostat housing. Check if the water pump has been changed; it’s best done at around 50,000 miles. Check the plastic lower radiator support – it’s prone to kerb damage.

TRANSMISSION - Check the clutch operation – failure as early as 20,000 miles isn’t uncommon. Worn synchros are rare so graunching suggests seriously hard use. Feel for a harsh shift on autos, often caused by a faulty valve body which could require a rebuild or replacement of the gearbox.

SUSPENSION AND BRAKES - Check the front wishbone bushes, which have to work hard. The anti-roll bar bushes have an easier time.

Also worth knowing:

Earliest R56s are 12 years old and the suspension, while sophisticated, isn’t the most adept and will probably be in need of a refresh. For less than £1000, you can replace wishbone bushes, springs and dampers with upgraded polyurethane bushes, Koni shocks and Eibach springs.

How much to spend:

£2300-£3495 - Launch cars with around 100k miles, generally good histories and in serviceable condition.

£3500-£4995 - Lots more lower-mileage 07 cars (circa 75k miles), with more lower-mileage 08s and 09s towards £4995.

£5000-£6995 - Very low-mileage 07s but many more 08 to uprated 10-plate cars with decent mileages.

£7000-£8995 - A good choice of proper 10 to 13-plate cars.

£9000-£10,500 - Plenty of low-mileage 11 to 13-plate cars here, the most expensive being a 2012 with 19k miles and £5000 of extras including powered panoramic sunroof.