Is a diesel estate the UK's best hot hatch?

Ford has produced a refreshed Focus ST. Light smattering of applause, happy face. We like the ST in the UK, the combination of relatively cheap power, everyday usability and B-road talent marking it out as a bit of a blue-collar hero. This time, it's not a revolution, keeping the previous 247bhp 2.0-litre EcoBoost, but gaining the midlife surgery of the mainstream Focus with a larger grille, new lights front and back and a slightly lower and wider stance, butched-up in ST guise with big wheels and a sharp-looking bodykit. It's no faster than before (0-62mph in 6.5 seconds, 154mph flat-out), but Ford claims to have improved the driving experience by introducing all-new front springs, new dampers for both ends, rewired EPAS power steering for better steering feel, reinforced engine mounts, tweaked Electronic Torque Vectoring control and a new set of Michelin tyres. There are three versions: all STs get Recaro seats, 18s, DAB and aircon. The ST-2 gets LED running lights, climate, part-leather interior and a heated windscreen for £1,500 more; the ST-3 adds £1,300 extra on top of that for fancier-again full-leather electric seating, bi-xenons and different alloys.

So far, so entirely predictable.

Pictures: Justin Leighton

This feature originally appeared in the February 2015 issue of Top Gear Magazine

There is, however, a curveball. And it comes in the shape of the 182bhp Focus ST TDCi. Of course, sporty hatch diesels aren't exactly cutting-edge thinking - the VW Golf GTD looming large here - but this is the first time that Ford has offered a diesel ST in the Focus range. An unsurprising marketing move, since the UK's enduring love affair with diesel means that 49.8 per cent of new cars sold in 2014 run on the stuff, outstripping petrol percentages of 48.8 per cent of registrations (if you think my maths doesn't add up, the other 1.4 per cent is made up of alternatively fuelled vehicles). Also unsurprisingly, it's a bit slower than its brother (0-62mph in 8.1 seconds and 135mph), but manages a decent chunk of extra mileage per litre of fuel: 67.3mpg and 110g/km CO2 versus the petrol ST's 41.5 and 159. Again, nothing very new in terms of the calculations you have to do to work out which suits. Except that the pair cost exactly the same, starting at £22,195. Which means that you're faced with the very real, very tricky decision between power and economy - heart versus head. With UK fuel prices dropping on a weekly basis at the time of writing, maybe this diesel hot hatch isn't so much late to the party as turned up on entirely the wrong day.

Of course, there is always still a host of factors to take into account, and the oily ST obviously has more than half an eye on the fleet sector's benefit-in-kind tax rules with that low CO2 figure. But when you're getting upwards of 50 per cent better fuel economy - official figures tending to be more easily replicated in a diesel - it's a hard one to ignore. It also looks identical to the petrol-powered equivalent (you can have either in extra-practical estate guise for £1,100 more, as we have here), apart from the dials in the cabin. Seriously, you wouldn't know unless you popped open the fuel cap.

It's of vital importance, then, to figure out what it's like to drive. And first impressions are... mixed. And confusing. Start the car, and it makes a decidedly un-dieselly whumping noise from the centrally mounted sports exhaust. Whichis promising. But the enticing gruffness then immediately settles - especially when cold - into a familiar four-pot diesel chatter, which leaves you feeling a little cheated. Photoshop for your ears. After that, pull away on anything other than glass, and you'll notice that the ride is actually quite choppy, firm enough to annoy, despite having the same revisions as its petrol-powered contemporary.

Which is, again, not quite what I was expecting - fast Fords are usually a little more compliant than this. A healthy 295lb ft then follows, which restores your confidence somewhat, meted through a decent six-speed manual 'box. And then the weird noises return, with the TD ST (I refuse to call it the STD, for obvious reasons), sounding uncannily like a petrol-powered boxer-four as heard through a thin wall, or the mute of a small trumpet. It's obviously the result of some acoustic occultism, but you can't argue with the result: on the move, it sounds really quite nice. Which is most unexpected and leaves me more confused than ever. A diesel hot hatch that sounds good but doesn't? A diesel estate that rides like a street racer? I need a decent road and some thinking time in the car, so we head north to unravel the mystery.

Cruising on motorways and A-roads, you'd never know you were in the diesel, apart from an uncanny ability to pull sixth gear from low revs and a mild disdain for petrol-station forecourts, real-life mid-fifties mpg helping to see off the temptations of motorway services' convenience foods. Once off the main carriageways, the nibbly ride once again arises, making me think this car might well be a handful where we've ended up - the Forest of Bowland, north of Blackburn. Now, this area is often overlooked as a place to drive, but the views are spectacular and the roads... challenging. If you take the Slaidburn Road (B6478) out of Waddington and then left out of Newton-in-Bowland and track up towards Abbeystead, you end up with a mix of moorland top roads and strange, technical little back roads. Quite the combination. Many are single-track, most have the kind of undulations that would make a roller coaster vomit. They are also prone to camber, potholes, unguarded edges and free-range sheep. None of which are particularly conducive to fast progress in a car with too-hard suspension.

The Focus is, initially, a bit frenetic. It's been raining heavily, and - on greasy roads, in the lower gears - there's a fair amount of wheelspin and a surprising amount of torque-steer. These roads crown heavily towards the centre and the edges tend to be cracked and pitted like rotten teeth, so suspension has to work hard to keep the car gripping and confident. The sightlines are also on the blind side of marginal, with decently throat-tightening lefts and rights camouflaged in the shadows of crests like geographical magic tricks. You can't take anything for granted, and a car that does exactly what you want it to is vital, lest you find yourself zigging when you should have zagged and end up upside down in Langden Brook.

The Focus is not very comfortable. Both literally and figuratively. It steers well, responds to inputs faithfully, but it gets pulled around by the roadway, bullied by the inconsistency of the surface. Smooth roads are joyous - enough lean to let you know what's going on, enough grunt to haul you through the tighter corners without resorting to a lower gear - but in the tricky stuff, where a hot hatch should really shine, it feels subtly incomplete.

Which is where I get a bit annoyed. And drive a little faster. It gets intense. The sheep look worried. And just when it should really fall apart, magically, the Focus resolves. It turns out that when there's enough vision to get a clear idea of the road ahead and I can carry a little more speed, the Ford tidies up considerably. It seems that the harder it works, the better the ST's suspension feels. Give it load and purpose, throw it a bit harder, and the Focus suddenly wakes up, absorbs better with more aggression, hunkers down where it was skipping. The tyres work harder, and the balance is actually very neutral - much more so than you expect in a front-wheel-drive car - even giving a hint of lift-off oversteer. Only a hint, mind. The roads are not wide, and the concerned sheep look dense.

In fact, go fast enough to get that suspension doing what it's supposed to, and if you can forget the low-rev limiter, the combination of subdued engine thrum and pleasing natural pointiness means you can almost not remember that you're actually in a small diesel estate car. But it's the same old argument. A diesel four-pot might be good, but it's still a diesel. It can only ever be good for a diesel. It's to do with the engineering of the motor itself: a compression (diesel) engine, where the cylinder compresses the fuel/air mixture until it explodes rather than using a spark plug, runs at much higher pressures than a petrol. The result is - generally - heavier internal components and more inertia, lower revs and less response. Diesel also burns more slowly than petrol, giving a meatier, if less instant, thump and a bolts-in-a-washing-machine timbre to the vocal range. Of course, turbos and metered fuel injection ameliorate some of the issues, and diesels offer hugely rewarding amounts of useful torque, but until you get into V6 or V8 territory (usually allied with a slick auto), a diesel engine never really feels as satisfyingly sporting as a petrol.

Which leaves the Focus ST TDCi in something of a hole. The occupier of a very particular niche. Given the nature of the UK market, the cost of fuel and the relative costs of the two versions of the ST, as a private buyer with a love of hot hatches, I'd be sticking with the traditional petrol variant, no question. It's significantly quicker, and I suspect it'd provide more traditional thrills on a favourite B-road blast. The relative inefficiency would be offset a little by cheaper petrol prices, and a lot by the enduring satisfaction. But, if the diesel-powered version was the semi-sporty thing that you can mollify the business manager with by telling him that it's a battleship grey 2.0-litre diesel Focus estate, then it's by no means a bad thing. It's just a bit more practical than desirable.