What to do if your car stops working somewhere you don't know well.
Pull as far off the road as possible and turn on hazard lights immediately, then set out a warning triangle if you have one. Contact your rental company's roadside assistance line first, since they can often dispatch help faster than a general tow service.
If you're in a remote area with no signal, stay with the vehicle rather than walking to find help, since a car is far easier to spot than a person on foot. Keep your rental agreement and documents handy, since the assistance team will likely ask for them.