Cycling or driving rather than walking?
We tend to walk routes in the Costa Brava that are not normally drive-able (generally we avoid traffic) but they are often accessible by bicycle with good options for mountain biking. Routes here rarely have gates and we've not seen stiles or other barriers as such and we regularly see wheel tracks on the paths even on the steeper rockier paths through the woods. Some of the dirt track routes would be accessible by 4x4 (just don't ruin it for the rest of us).
Mountain biking in the hills of the Gavarres is a very popular activity, particularly outside the summer months. And the area around Girona is considered a Mecca for professional road cyclists because it offers a large number of different types of routes on quiet roads in a wide area, from flat plains to hill-circuits over the Gaverres, or a full mountain climb up to the Pyrenees.
Even for softie cyclists - the plains around Pals, L'Estartit, Sant Pere Pescador and the Via Verde cycle routes (eg the Ruta de Carrilet or the Ruta del Tren Petit) offer a wide range of easy-to-ride routes connecting beaches and pretty villages.
For off-road cycling, much of our walking is done on tracks and there are hundreds of BTT tracks - (Bicicleta Tot Terran) with routes into the hills and marked paths down hills and many groups leave trails marked with flour or flags tied to trees.
Driving is more challenging as many of the tracks get pitted with deep holes after the winter rains, so anyone driving off-road will need a robust 4x4 and will face the problem that sometimes a road either just peters out, or narrows so much that you can't go any further and it is extremely easy to get lost unless you really know where you're going. So if you're trying to find a remote farmhouse or viewpoint, make sure you have good directions and don't gamble going into the woods on spec.
