In my review of the Ford Focus EcoBoost I guessed that the 40mpg-plus-change I achieved with it on a long run was about 5mpg less than the 2.0 TDCi turbo diesel could have managed. It turns out that I was being pessimistic.Comparing fuel consumption figures on different roads is a notoriously wobbly business, so you might view what I'm about to say with a measure of scepticism, but the fact is that it was very easy to beat 45mpg in the diesel without really thinking about it. With a little more concentration it wasn't difficult to nudge past 50mpg, which is close enough to the official combined figure of 56.5mpg to put a smile on my face.Long gaps between fuel stops aren't the only reason to be pleased with this car. I've driven diesel Fords which were ridiculously noisy, but that was a long time ago, and besides, the wench is dead. The Focus TDCi is so quiet and refined, even when you're ignoring economy altogether and making use of its 138bhp power output, that I could imagine (though I never put this to the test) that a not particularly car-savvy passenger might doubt that it had a diesel engine at all.That 138bhp figure might not get your juices flowing, and it's certainly not enough to turn the Focus into an exciting car, but really and truly it's as much as you need. And there is enough power at very low engine speeds - including well below 1500rpm - for you to be able to avoid making many gearchanges. This, along with comfortable seats and the lack of undue noise, makes the Focus diesel a very relaxing car to live with.It would be even more so if the ride quality were better. In most cases it probably is, but the test car (like every third-generation Focus I've driven so far) was fitted with low-profile tyres on 18" wheels, which naturally enough made the ride fussier than it needed to be and are to be avoided by persons of refined sensibilities.The 2.0 TDCi Focus will set you back about £1000 more than either the EcoBoost or the 1.6-litre diesel. If running costs are important to you, the only choice is the 1.6 diesel, which is certainly slower (by exactly two seconds from 0-62mph) and probably less relaxing but is much more economical and costs hardly anything to tax. Then again, the 2.0 TDCi has a CO2 rating of 129g/km, so the Chancellor won't be charging you much for owning that either.For other pertinent comments about the Focus range, take a look at our launch report or the EcoBoost review. Or, if you're pressed for time, here's a quick summary: the current Focus is available with a tremendous array of safety aids, room in the back isn't what it might be, luggage space is actually less than it was in the previous model, and visibility, particularly at the rear, is lamentable. Engine 1998cc, 4 cylinders Power 138bhp Transmission 6-speed manual Fuel/CO2 53.3mpg / 139g/km Acceleration 0-62mph: 8.9sec Top speed 129mph Price £20,745 Details correct at publication date