The Kia equivalent of the Golf is the C'eed, both C-segment cars. The Golf is not a subcompact.
I believe the Kia Rio is a B-segment supermini class car that's more akin to a Ford Fiesta (which you guys don't get anymore) or a VW Polo (um, not sold there either). So it makes sense the Rio would be cheaper, smaller class of car than the Golf.
the Golf is a bit bigger, but not much...the Rio5 is larger than the Fiesta (which is no longer available)...i test drove a Fiesta when i bought the Rio5...it is small (not that the Rio5 is huge, but it is bigger inside than the Fiesta, it is noticeable right away)...the Golf is likely a similar that way (comparing it to the Rio5)...my point is, the Golf is a really good car, but $35k is certainly getting up there...and for someone looking for a well equipped small car who is looking for lots of features, but still on a budget, that Golf can get up there...example, a fully loaded Rio5 in Ice Blue Metallic is $350.59 for 84 months...total all in price is $29,449.56...a Golf Execline (i left off the safety package since those features aren't included in the Rio5 to try and keep them as close as possible), is $539.52/month for 84 months...that's almost $200 per month more, for 7 years...total cost is $45,319.68...a difference of $15,870.12...that's a significant price difference, and while i'd agree the Golf is a better driver's car, it's hard to justify a difference in price of almost $16,000...you can almost buy a base trim Rio5 with the difference in price...aside from the price gap of the vehicles themselves, is that is made larger by the interest rate difference...the cost of borrowing on the Kia is $443.59...it is $7135 for the Golf...that's $7k you're simply handing to the bank and getting nothing to show for it.