John a écrit :
We would like leave Lyon in the morning to go to Digne-les-Bains to see the
Tour De France stage 12 pass by, then continue on to Nice that same evening.

I doubt you can catch the Digne-Nice train the same day.

How is this best done? Train or coach? I understand cars in France usually
cannot be rented for just a single day.


I have not had the opportunity to rent a car recently. But in the past,
I had to rent a car for a single day without any problem.
I tried a Lyon-Nice reservation on the AVIS reservation site, and it
seems possible (not really a bargain).
http://www.avis.fr/
Agence de départ Lyon, Gare TGV de St Exupéry, Aéroport de Saint Exupéry

Téléphone ( 04 72 22 75 43 )
Horaires d'ouverture à la prise du véhicule 07:00-23:00 h.
Agence de retour Nice, Place Masséna, 2 avenue des Phocéens

Téléphone ( 04 93 80 63 52 )
Horaires d'ouverture au retour du véhicule 08:00-12:30, 14:00-19:00 h.
Catégorie de véhicules Catégorie C (ex. Renault Mégane)

Détails du prix
Prix

Possible with CITER too (80,6€)
http://reservation.citer.fr/
152,89 EUR