Five minutes into our test drive of the Kia Ceed 2 EcoDynamics, and we think for a moment that we’ve stalled. Evidently we have cloth for brains because the whole purpose of our test is to assess the Intelligent Stop-and-Go facility (ISG) that is responsible for the lifeless engine. Thankfully a simple dip of the clutch is all that’s required to get things moving again.

Just like the stop-start features you’ll find in much pricier cars from the likes of BMW and Land Rover, ISG is a clever fuel-saving box of tricks. When the car is stationary, the engine stops turning and so ceases to burn fuel. The engine then rapidly restarts, automatically, when the driver is about to set off.

ISG performs other, subtler sleights of hand too. For example, under acceleration, the alternator is decoupled to minimise engine load. Instead, the alternator charges the battery when the throttle is closed, squirreling away energy from the car’s momentum during engine braking.

It’s quite a surprise to find such sophisticated features in a five-door, green-label hatch costing just £14,500 on the road.

We found the Ceed’s ISG system worked very smoothly and predictably. We obviously can’t bear direct witness to the alternator shenanigans, nor confirm that the system measures the crankshaft rest position to optimise the restarting process. However, we can report that the engine cuts out reliably when stationary with the box in neutral and the clutch up, assuming the coolant is at least a little warm. A small green “auto stop” indicator appears on the dashboard to remind forgetful fools like us of what’s going on.

Push the clutch in a fraction and the engine restarts quietly and promptly before you can finish engaging first gear.

Coast in neutral at speed and the engine will keep turning, as it’s supposed to. Touch the clutch at the very instant the engine dies and it will leap back to life without confusion. We try and fail to fool the system into staying dormant when it ought to be awake.

Our two-hour test route through Central London has taken us less than 20 miles and seen us halt more frequently than a geriatric sloth, and the engine has stopped and started perfectly for every traffic light, bendy bus and blocked yellow box.

Given the complexity of the ISG system, it’s reassuring to note that any faults would be covered by Kia’s unrivalled seven-year, 100,000-mile warranty. The only caveat is that the car has to be dealer serviced to remain covered.

We’re not sure how much fuel ISG saves in the real world, but it certainly slims down the official consumption figures. ISG accounts for 5mpg of the 1.6 CRDi EcoDynamics’ combined cycle score of 67.3mpg and lops off 9g/km of CO2 to bring the result to 110g/km. This puts the car into Band B – not bad for a Golf-sized five-door hatch – and for company car buyers brings a host of tempting tax benefits.

The figures are aided by the Ceed EcoDynamics’ Michelin Energy Saver tyres, a smooth-shifting six-speed manual gearbox, and helpful up- and down-shift indicators on the dash. With six ratios on offer Kia has been able to avoid the odd gearing that blights so many green-label specials. Fourth is fine at 30mph while the tall sixth keeps revs economically low on the motorway. On a blast up and down the M11 the Ceed proves to be a relaxing cruiser, with the murmuring engine and well controlled wind noise contributing to a peaceful interior.

Off the motorway, back in the urban gridlock, we have plenty of time to prod and poke at the Ceed’s recently revamped interior. It’s best summarised as a mixed bag. The dashboard and centre console are attractive and pleasant to touch, but the door furniture looks like it comes from another car, with boxy shapes and hard, shiny plastic.

Similarly, the steering wheel and centre armrest look lovely trimmed in stitched hide, but feel more like vinyl than cow-hide under your hands. The wheel is at least well shaped and includes a useful range of buttons – including the first controls we’ve seen set into the 6-o’clock spokes at the bottom of the wheel. When you try to use them, though, you realise why most other makers leave this part of the wheel unadorned – unless you have double-jointed wrists or very long thumbs, you have to let go of the rim to reach them.

Gambolling away from the lights, the 89bhp diesel engine proves throaty but eager and surprisingly refined –very little vibration comes through to the cabin even under high load at low revs.

Kia says ride quality was improved as part of the Ceed’s recent facelift, and we can’t imagine how bad it must have been before – the current car keeps the occupants fully informed of every pebble that passes under the wheels. A little more compliance would be more than welcome in what is by no means a sports-oriented car.

As we hand back the keys, we are left with two distinct impressions. One: the ISG system works beautifully and could be a real boon to city drivers. And two: those same city drivers will curse the harsh ride as they shudder over the frangible patchwork of our urban road network.