Where did you get that text from?
This is a weird usage of the word подземно. I don't think a native speaker would use it like that. Or if she does, it would be improper... as in she couldn't think of the right word, so she used this one.
However, I can definitely say that the author meant that driving in Bulgaria seems very bad compared to Germany. Unpleasant might not describe it well since unpleasant in this case would suggest that you are the driver (or at least IMO) while you might actually be a pedestrian or a passenger.
P.S. Also "да СЕ изкажа" sounds a little off here...
Защо да харчим пари, които нямаме, за да купим неща, които не са ни нужни, така че да впечатлим хора, които не харесваме?
I don't even remember what standard deviation is.
BezierCurve: It's some important part of sadistics, I believe.