At one point, SNCF estimated that average speeds of 130 kph (about 80 mph) were needed for rail to be a really compelling alternative to the car. That line of thought led, ultimately, to the TGV.Try a more realistic comparison which includes travelling from origin to station and station to destination, plus accounting for padding to minimise the risk of missing the train, and compare that to the car, you may find that it is a lot closer.
Musing on EuroCity, which had a formal definition of what constitutes an intercity service, is interesting for this discussion. To take Wikipedia's list, which appears to originate in a Thomas Cook European Timetable, they were:
- train through two or more countries
- all cars air-conditioned
- stop only at stations serving major cities
- stops scheduled to last no more than five minutes, in special cases up to 15 minutes
- food and beverages available onboard (preferably from a dining car)
- conductors speak at least two languages, one of which must be English, French, or German
- average speed (including stops) above 90 kilometres per hour (56 mph), exceptions for routes including mountainous terrain and train ferries
- trains must complete their journey between 6:00 am and midnight (i.e. depart after 6am and arrive before midnight)