Thanks guys, some interesting points of view. I have to admit I wouldn't mind owning one of each
My wife has fallen in love with a Hijet and she has her Aygo on the market now so that she can buy one. Never imagined I would live in a Daihatsu-dominated household

I never considered the rally4 mainly because I thought the handling benefit would be outweighed by the slower pace and heavier fuel thirst. Is there a noticeable difference in mpg between the 2 and 4? The YRV Turbo is quite heavy. I struggle to get 33-35mpg even with very calm toned down driving.

There are also the finer pros and cons:
There is loads of room in the YRV with the seats down. I cant imagine the Sirion matching this.
There are electric folding mirrors on the Sirion - if you only have parking on the street you know how irritating it is to manually fold the mirrors in and out every time you park off!
If we have another snowy winter - the 4wd will prove VERY useful, I was sliding on ice every morning with the YRV
The Sirions have chrome trim (thats definitely a pro! - depending on your age and what styles you grew up liking hehehe)

Maybe we should arrange a "timeshare" swap cars for a month or 2 at a time...
Just out of interest is anyone around the Bristol area?

I am enjoying reading what all the different experiences have been with the various models and cars. From my point of view, I agree with some things and disagree with others.

I definitely agree that some engines have an inherent "flat spot" or even a "flat range" at or below a certain rpm. Even some models of the Honda Civic type R suffered from extremely sad low rev performance. Their V-tec system was supposed to have prevented this from happening, but with the capacity engine and weight of the car, the formula only worked well when revving it up madly (with good results admittedly).

Then on the other extreme, you get a Nissan engine like the SR16VE, their variable valve and timing engine, 1.6l but with loads more torque than the B16 1.6 Honda engine. Peak power was similar, but the power and torque delivery over the rev range was completely different. On the road, the SR16VE was easy as a daily driver with enough torque low down, with enough power higher in the rev range (but at 1500rpm lower than the Honda though).

I can imagine similar shortfalls with the DVVT-i system in Toyota/Dai engines. However I do believe that they offset this by modifying the profile on the exhaust cam. Different cams are an easy way to change the characteristics of the torque/power delivery. Would like to test the theory with a rolling 2nd gear pull between a YRV turbo, a Rally 2 and a normal Sirion or YRV 1.3.

The other interesting point is the torque on the YRV Turbo. It doesn't spool up as fast as some of the other turbo cars I have owned. Also, unless you are driving very smoothly (which is the majority of the time), if you need to accelerate quickly or go uphill, if you push to hard on the accelerator, it has a delay and then a very sudden spool up and huge jump in torque. Can lead to a bit of a surprise if you're not expecting it! I would be interested to drive a Rally 2 to see what the difference is. I actually think that for a few seconds the Rally would edge in front, and only once the turbo spools up in the YRV, then it will be overtaken by the YRV and should stay that way (the YRV is very quick between 40 and 80mph).

Then again, I could be wrong about all of this, just my thoughts on the matter...