If you're looking for a meeting place or a good stop around ½ or halfway between Lyon and Turin, you can try Saint-Jean-de-Maurienne, France, which is about 2 hours southeast of Lyon, or almost 2 hours west of Turin.
About ¼ or a fourth of the way, you can stop at La Motte-Servolex, France. This is about 1 hour east of Lyon.
About ⅓ or a third of the way, you can stop at Chambery, France. This is about 1 hour east of Lyon.
If you drive straight through without stopping at all, the total distance is 306 km. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 3 hours, 41 minutes.