Do not be swayed by Atkinson cycle. Maybe you will get 4mpg more in a Mk 4.
Will take many years of driving to recoup the extra cash you shelled out.
My MK3 will give 45mpg on a run if you hypermile it, otherwise expect 36.
Seats are awesomely comfy. Two years and has been faultless apart from rusty exhaust and weeping radiator, both to be expected.