Some background on the genesis of iDTGV and Ouigo...
The idea of liberalisation of rail services has been present for the best part of the last two decades, pushed by the EU, even though the French government has tried hard, and so far succeeded, to prevent it.
While DB has chosen to force-fill the taktfahrplan so that no useful paths are left available for open-access operators, SNCF, like the proverbial judoka who leverages energy from its enemy rather than fighting against it, has taken a head start with new business concepts (OuiBus shares the same philosophy).
iDTGV was the first experiment back in
2004. Its aim was to solve the dilemma that new open-access operators would not be bound to the very worker-friendly rail bargaining agreement, thus being more competitive.
This has led SNCF to set-up a private company with labour conditions (and costs) in line with "vanilla" private companies. Short-formed trains would be doubled with iDTGV sets staffed with iDTGV crews. Thus no drivers would be required and the company can be launched without the market being formally liberalised.
It was also used as a laboratory to test innovations used in the airline industry, such as in-train entertainment.
However, the enhanced rail collective agreement agreed with a few weeks ago now applies to all rail companies (SNCF as well as future hypothetical open-access operators). At the risk of steering off-topic, I add that the government was keen to sign this agreement, being entangled with significant opposition to the wide-reaching labour law that was being introduced into parliament.
So one could say the iDTGV experiment is now somewhat useless, as SNCF legacy services are now competitive... at the expense of competitiveness of the rail sector as a whole.
OuiGo was launched much more recently, in
2013, as SNCF, being faced with the erosion of TGV profit margins, tried a new, more productive trainset organisation by:
* reducing lost time at terminii (from 2 hours to 40 minutes, somewhat closer to Shinkansen efficiency
) ;
* densifying trainsets: no buffet, full 2nd class throughout and more compact (regional train style) seats ;
* increasing the efficiency of the maintenance regime. For instance, a train is allocated to one depot and maintained at night-time only, instead of roving between numerous depots. Some of these innovations have since been brought to SNCF mainline.
The distribution system has also been streamlined by selling tickets on the web only and using an off-the-shelf distribution system (the same as most low-cost airlines in fact).
Compared to iDTGV, OuiGo's is staffed by "classic" SNCF agents, with the same benefits.
This new organisation enables much lower prices: 30% cheaper on average, from 10 EUR to a maximum fare of 85 EUR.
OuiGo has so far been a huge success with 99% load factor last summer with most of customers being induced rather than cannibalised from classic TGV services.
However, the development of OuiGo has led to the withdrawal of low profitability cross-country services, with reduced convinience for customers. For example, services that used to terminate in Lille now terminate in Tourcoing which is quite far away from the action! (and with a 30mn check-in deadline to boot)
TL/DR: both companies were tried to modernise historic railway practices, on two key areas:
personnel costs for iDTGV and
trainset productivity for OuiGo.