No big deal. I took mine down to Alabama the week after I got it. Having tried different speeds I settled on 112 kph as best compromise between speed and fuel use. At 125 it was working too hard on hills [105 up, then 130 down].
Mine's a CDI so maybe not applicable if yours is newer.
We recently took the tour of eastern Canada. Starting from NH to Portland, ME and the CAT ferry across to Yarmouth. From Yarmouth to Halifax, up around Cape Breton to Sydney then on to Charlottetown on PEI, drove to Saint John then Quebec City. Our final leg took us back home to NH. For the early legs of the trip we took the senic drives along the shore.
The trip totalled out to over 2200 miles.
The roads were good, the traffic reasonably light and we stayed near or slightly above the posted speed limits. The weather was spectacular and we drove with the top down quite a bit.
It was usually more difficult to find a good restaurant than gas.
Overall, it was enjoyable and we had no issues with the car.
If you drive in auto mode, your smart may come up a little short on high-speed hills in 5th gear because it won't downshift automatically until the speed gets down to the 60-65mph range (100-110kph?). Just watch for speed drops on high-speed inclines and shift into 4th to keep up speed. I just did 3800 miles traveling between opposite corners of the US.