I've had five RX's over the years and generally more than happy. I did have a dicky 350 (bad fuel consumption <20mpg) and ended up trading it in for a 400h after three months which served me very well for 85k and five years.
I bought a new 450H on the basis on better consumption and more power. However it is averaging 30.8mpg over 10k against the 400h 's 32mpg despite being driven with carpet slippers.
The garage don't know what to do about and seem to think this is a common problem. On top of that it is much slower , apparently down to the rebalancing of power between front and rear axles which avoids a steering problem with the 400h.
All in all I am quite dissatisfied with the situation, especially as I still have access to the 400H and it continues to delight. Any solutions??
