Montpellier is a city in the South of France.
Apart from an attractive city in itself, it is situated next to a main highway A9/E15 connecting cities such as Perpignan and Barcelona to the South, Aix-en-Provence and Marseille to the East, Lyon and Paris to the North, and Toulouse and Bourdeaux to the West.
In Montpellier there isn't a Péage so best thing is to make your way as close to the highway A9/E15 as possible.
Option 1: First option is to get to Place de L'Europe, for example by taking tramline 1. From there you can already see signs to the highway. You can either follow those signs and the main road (Avenue de Président Pierre Mendes France) for about 15 to 20 minutes, or get a ride from where this road starts to either your destination or to a better location further up the road, at the roundabout where the main highway A9/E15 actually connects to the Avenue de Président Pierre Mendes France.
note: there is not a very good spot for cars to stop, but they stop at the roundabout for traffic with enough time to ask drivers for a ride, and for them to open the door.
Location on the map of the roundabout]
Option 2: A second option is the roundabout off Avenue de Palavas. However there is no good spot for cars to stop at the roundabout, and nowhere on the ramp either. Zac Stewart waited for an entire day for a ride to Perpignan without luck and shamefully retreated to the train station.
Going North or East: Lyon, Paris, Aix-en-Provence and Marseille
Follow the same directions as above.