James says - a few trip notes:
I visited Helsinki briefly in 2009 as I was spending a week travelling around various cities in Scandinavia. I would love to return and do it more justice, but there is still plenty that I would want to see outside the city without needing a car.
Around Helsinki without a car
Conclusion — if your main priority is to drive around the Finnish landscapes, then picking up a hire car at Helsinki airport is probably the best option, although we firmly believe that Helsinki is massively underrated as a city in its own right. Once you start allowing time to enjoy Helsinki and its surrounding area, then the car becomes a lot less useful, especially as the standard of scenic railways in Finland is very high.
Do you need a car in Helsinki? No! For all the reasons above, we advise at least looking at other options before automatically getting a hire car.