The manufacturer now has, or will have, D-4D engines in all its cars from the Yaris and the new Corolla, through Avensis and up to the Land Cruiser. It expects to see public sector, driving school and user-chooser fleets adopt the Yaris D-4D when the car goes on sale next March.
Shoehorning a 75bhp 1.4-litre common rail diesel engine into the Yaris is essential for European sales, and across the continent it expects to sell 36,500 diesel units a year, about 35 per cent of all Yaris models sold. In the UK, the D-4D will account for 6,000 units, or 20 per cent of total sales.
And as such, a larger share of the development work on the car has been done in Europe than in the past, where the Yaris has been a key car for Toyota, part of the firm's new strategy of evolving each model in its most important market.
Toyota is claiming some impressive statistics for the Yaris D-4D: fuel consumption of 64.2mpg with a range of 630 miles, a CO2 figure of 117g/km, and 133g/km for the Yaris Verso. It's too early to say whether these figures will bear out, but they do put it up there with the best in class, as do on the road prices.
Estimates suggest the D-4D models will be around £1,200 more expensive than the petrol siblings, which means starting at about £8,300. It should therefore be at least £300 cheaper than the Citroen Saxo 1.5D Desire, and Renault Clio 1.5 dCi 65 Expression and a whopping £2,500 less than the Volkswagen Polo 1.4 S TDI PD. Add to that a reputation for being mechanically sound, and the Yaris D-4D would appear to be a strong contender in its field.
Service intervals should be every 20,000 miles, with a health and safety check every 10,000 miles. There are no wholelife or residual value estimates yet, but the petrol Yaris is holding up well against the competition in those areas, so expect no hidden shocks on that front.
As you would expect for a B-segment diesel car, there is always going to a fair amount of noise from a diesel engine vibrating into the cabin. There just is not the space or soundproofing to totally deaden it, but Toyota has done as good a job as anybody of keeping it to a minimum.
At motorway speeds though, the noise does tend to die away, which means a long distance blast should not leave the occupants' heads buzzing like a tuning fork when they reach their destination.
Toyota has also been keen to retain the sparky handling of the Yaris, which it has done. Diesel engines are heavier than petrol engines, which can lead to understeer trying to get the bigger lump around bends.
Toyota has used aluminium alloy in the cylinder head block and intercooler to ensure the D-4D motor only gains 15 kgs, and has uprated front suspension to cope with the extra weight and retain its handling attributes.
The D-4D manages a top level of 125 lb-ft of torque between 2,000 and 2,800rpm, but 90 per cent of that is also available as low as 1,800rpm. This means the Yaris has a good, stable level of power throughout the range, and does not have much of that yo-yoing acceleration that some diesel engines suffer from.
Acceleration from 0 - 62mph is 12.9 seconds with a top speed of 106mph, which again puts it near the top of the class - something becoming a recurrent theme with the Yaris D-4D.
The rest of the package is much as you would expect from a Yaris, with good interior space and that odd instrument display that makes the digital readout look like it is housed about three feet away. I would prefer the gearbox to be less of a throw from cog to cog though, and the seats are not wide for the more portly backside.
But for the money, the Yaris D-4D is a lot of car that provides a winning combination of style, frugality and refinement. It will make an interesting alternative to the new Polo and Fiesta when they hit the roads next year.