The introduction of the second-generation Kia Soul earlier this year made it almost exactly no more likely at all that I would ever spend my own money on one. If, however, such a thing were ever to happen, there's a strong chance that is is the one I would buy.The main reason is that it uses a 126bhp 1.6-litre diesel engine rather than the slightly more powerful but otherwise inferior petrol engine of near enough the same size.This is not because of any anti-petrol bias. Sometimes I prefer petrol versions of a particular car, sometimes I prefer the diesels. In the case of the Soul, I'm going for diesel every time.Why? Let me count the ways. One, it is, of course, much more economical, with a combined EU figure of 56.5mpg rather than the petrol's 47.1. You'd have to travel for many miles each year for this and the lower Vehicle Excise Duty bill to compensate for the £1600 list price premium, but I do a lot of long journeys so I'm okay with that. Even if I didn't and wasn't, though, there's always . . .. . . two, the slightly superior, though still not very good, ride quality of the diesel Soul (it shouldn't be that way, but it is) and . . .. . . three, the utter gutlessness of the petrol engine unless you rev it to the red line in every gear, which, as a careful and sensible Soul driver, you're not going to do. The diesel may have a lower maximum output, but it has much more power when you need it.I would still prefer not to have a Soul at all, largely because of the lack of practicality (small luggage compartment, narrow tailgate, high sill) and the stupid rear window design, but I would grudgingly admit that there are people who won't mind these things and are captivated by the looks, created by the folk at Kia's American design studio.Among the "ordinary" Souls, not including the Mixx and Maxx special editions, this is nearly the most expensive model, falling £1500 short of the same car with automatic rather than manual transmission.No Soul is sparsely equipped - they all have DAB digital radio as standard, for example - but the Connect Plus has satellite navigation, a reversing camera and an Infinity audio system with mood lighting for the speakers (a bit cutesy for me, but fair enough) in addition to the front foglights, heated door mirrors, storage box and Bluetooth set-up also available on the £1100 cheaper Connect.The list price is a fairly modest £17,500, and in addition to everything you already know this includes Kia's remarkable seven-year/100,000-mile warranty, all of which means that I like the deal more than I like the car. Engine 1582cc, 4 cylinders Power 126 Transmission 6-speed manual Fuel/CO2 56.5mpg / 132g/km Acceleration 0-62mph: 10.8 seconds Top speed 112mph Price £17,500 Details correct at publication date