This is a really interesting topic. We've been keeping a close eye on the next Jazz as a potential replacement for our GD which will be 10 years old by the time it arrives here.
I have a lot of faith in Honda whenever it comes to engine technology but I'm not sure where they are with turbo technology given that they are relatively new to forced induction in consumer cars. HJ's reviews seems promising though at least in terms of refinement as performance is never a problem with turbos but getting that performance with decent economy and driveability is. And this is the area that I'd be most interested in particularly given my experience with small engine turbos from other manufacturers.
On paper they are great, good economy, decent power and good low end torque as well as low CO2 = low road tax. However having driven the VW 1.2 turbo and several other larger engine turbos, I can't help but feel a little sceptical about the real-world MPG figures. As it was just impossible to get near to the figures quoted in the brochure, even when the salesman was driving. I think the trouble is, unless you’re content with driving without stretching the legs of the turbo, then you might just get the claimed economy figures, but as soon as you start putting your foot down a little (and you probably would have to with small engines), the economy figures goes out of the window as you’ve effectively transformed a 1.0L to a 1.8L.
There is no doubt that small engine turbos are the way forward for small cars, but to have reasonable pick up at traffic lights or to go up inclines a small NA engine will never be strong enough, you will need to use the torque from the turbo which always comes at a price - fuel. Unless of course Honda again has some tricks up its sleeves…
The obvious solution to this is to bolt on a hybrid system but whilst the hybrid technology is well proven, it is still relatively expensive. And to introduce a hybrid system with a 1.0L turbo for example, may just bump the price beyond the reach of Honda’s target customers.
I really hope Honda has come up with something new that will be a real game changer in terms of economy. Afterall, the last evolution from GD to GE was not particularly impressive.