Places to visit starting in Quebec City and going up the coast
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You'd have to be a little bit more specific. Which side of the St. Lawrence will you be driving on. And by driving up I assume you mean going east. (As silly as it sounds, that'd actually be driving down taking into account the way the river flows but I'm being fussy).
On the south shore, Snack bar D'Amours un Rivière-du-Loup is a fun stop for good poutine. You can get your dessert 15 mins later at Alibaba in Cacouna just where the 20 meets the 132. Fromagerie des Basques is your basic cheese producer. Not great but not bad either, that's in Trois Pistoles.