I'm assuming by the 163 and 155 motors you mean the different states of tune for the 1.6 petrol 4 cylinder this car comes with
there is very little to choose between them as they aer teh same engine with just a different ECU tune between then
Other things to consider are:
Sat nav system can be prone to leaving you circum-navigating roundabouts, unsure of which exit to take.
Shortage of R-Type diesel engines led to some very long waits for the car during the summer of 2010.
Hyundai appears to have stopped supplying a full-sized spare wheel in ix35s from 2014.
1.7 diesel KIA Sportages (same basic vehicle) suffering problems with cruise control.
Mysterious faults leaving 2.0 diesel 4x4s temporarily immobilised.
Trip meter sometimes re-sets on a refill of fuel, sometimes doesn't.
Report of noisy driveshafts on 2WD GDI versions.
Seems to be a problem of fuel filters of 1.6 GDIs getting blocked by emulsified fuel. For a GDI engine the filter has to be very fine, so if you fill with fuel that contained a high percentage of ethanol (biofuel), that is more prone to emulsify.
Report of aircon of Hyundai ix35 1.7CRDI failing on long trips: fan speed appears to slow although a lot of fan noise still being made and vent temp becomes warm. Can be cleared by turning the temp up for 2 mins and opening the window, but then the problem returns after 15 minutes.
Reported that Hyundai seems to have stopped supplying full sized spare wheels with the car from 2014. Now just a puncture repair kit.
22-6-2011: Notified by reader of two dealer service updates to 2.0 4WD: OOCS10 rear trailing arm bolts and OOCS16 ECU Upgrade. Since the ECU upgrade the reader's MPG improved from 39 to 46MPG.
19-5-2014: Just-auto.com repostes via AFP that Hyundai is recalling 140,000 Tucson SUVs in the United States and Puerto Rico because of an air bag problem, according to documents filed with US auto safety regulators. (The Tucson is sold as the ix35 in Britain and Europe.) There were no known accidents or injuries as a result of this problem, the company said in its recall notice to the National Highway Transportation Safety Administration. The issue relates to the bolts that attach the driver's airbag to the steering column. "During assembly, it is possible that the two bolts attaching the driver's airbag module to the steering wheel assembly were not properly tightened," the automaker wrote in its letter to the NHTSA. "If both bolts become loose and detach, the driver's airbag module could become detached from the steering wheel." Hyundai said the defect "could result in injury in the event of a crash." Hyundai said it was recalling 137,500 vehicles in the United States and 3,500 in Puerto Rico, from model years 2011 to 2014. The issue came to Hyundai's attention in December 2013, after reports of dealership service departments tightening the bolts under warranty. The automaker will ask owners to bring their vehicles to have the bolts checked