sorry in advance for a long post, if in a rush just read the first and last paragraph:)
just to give a outset view
so far i have driven 1000km
first lets define underpowered, right now everybody is mentioning it as a subjective thing, people's definition of underpowered may vary and does vary considerably.
to me objectively underpowered means when in a car (in a normal not speeding driving situation) a need ever arises to go full throttle to overtake or get out of a situation its underpowered. in gli sadly in many situations i found need to go full throttle the power was simply not there so according to me its underpowered because i can easily go full throttle at any time without any consequences the car never accelerates anywhere quick. this to me is also slightly annoying and dangerous as it can be a hazard while overtaking if you are used to driving bigger engined cars where you press the throne and there is immediate torque to finish the manuvre where as in a gli you'll have to wait a but for revs to build up, 4th gear at 60km/h try going full throttle you'll really struggle to even get pass 70 if you are climbing a bridge you must shift down.
now you probably get used to it and drive accordingly so dont be disheartened, it can certainly go anywhere in paksitan conquer any hill but that is not a compliment in it self as if a car sold in paksitan cant get up any public road then it should never be sold in the country in the first place.
so in a nutshell compered to 1.6 1.8 or city's 100hp 1.3 yes its underpowered as you can be in situations in normal driving where you wished you had more power just to complete that manuver more safely and more comfortably without any stress or notice.i am not talking about for thrill, its a family car anyway.
all other cars in my house are 1.8 and over so maybe i am being too harsh, its enjoyable and when you are in the right revs at the right time you actually have a decent amount of thrust. compared to our 2010 gli 1.3 i feel it more slower than that but its in the running stage and oil hasn't changed yet, that car is running on fully synethic mobil 1 so i think the new one will get better after running but maybe the bigger body and addition of catalytic convertor make it even slower than last generation.
purpose is not to worry you i am more than sure that you'll be 100% satisfied with the performance of your car under most situations only if you compare car head to head then you notice whether its underpowered, if in a hypothetical example there was only one car sold in the world and we looked at it alone underpowered word wont be in the dictionary even because there is no benchmark to compare too, so only when you fall into comparison does that issue arise, if you look at your car without regard to anything else you'll not find it underpowered and will enjoy it.