Any answer of a owner is welcome, do you feel a lack of power when driving the XB of these 3 models

If you care about ''power'' then yes, you will sense a lack of power. You could floor the thing in normal city driving in the LA area and it would not look like you were driving any differently than most people. Of course, if power is not your concern these older xBs had some pretty good gas mileage. The new xBs have larger engines, but are also larger in size and get correspondingly worse mileage.

well the problem is with scion xb and xa is from 04-06 they barely have any power! both engines they offered have less then 110hp

The 04-06 Scion xB/xA have 108hp & 105 lb. ft of torque. It is not a lot of power, but l have not had any problems, it actually has a lot more power then l thought it would. l have a five speed xA & l have quite a bit of fun with it & it gets great gas milage. l would imagine that the xB will be a tad slower because of size & weight, but not by much. An automatic feels like it lags to me, l test drove an xB auto. With a couple little mods, intake, exhaust & header, it gets a bit more noticable power, & still maintains mpgs.