Older Scots have gone from being the least satisfied to the happiest travellers.
Two thirds of over 65s who took part in a new Glasgow University study were happy with transport in 2010 compared to fewer than half 13 years earlier.
This was attributed to the money they saved from the introduction of free bus travel for the over-60s in 2006, encouraging them to take more trips.
Researchers also found the proportion of people satisfied with bus and train travel doubled from 32 to 64 per cent between 1997 and 2010.
The study, which is one of the first to show how satisfaction varies between different modes of transport, discovered more walkers and cyclists also became happy.
By contrast, the proportion of content car drivers and passengers fell from 72 to 66 per cent.
Possible factors include the stress of being stuck in more frequent traffic jams because of increased car ownership.
Dr Jonathan Olsen, who led the study, said: “Barriers to satisfaction could have been removed for older people, such as the cost of travel.
“Other evaluations of free bus travel have shown the policy produced shifts from car travel, which our study has shown has greater transport satisfaction.”
Gavin Booth, director for Scotland of watchdog Bus Users UK, said: “We know from feedback and regular monitoring that older passengers are making greater use of bus services, encouraged by the concessionary fares scheme and the widespread use of easily-accessible buses.
“These have given older people much greater freedom to travel for essential and leisure purposes, and this in turn contributes to a healthier lifestyle.”
Sustainable transport campaigners Transform Scotland said ministers should pay heed to the findings in their review of free bus travel.
Director Colin Howden said: “We already know walking, cycling and public transport are good for improving public health and the environment, and reducing inequalities.
“So it is heartening to hear these most sustainable modes of transport are those where people have experienced the greatest increase in satisfaction.
“It is interesting the national concessionary fares scheme has been identified as a significant factor in increasing satisfaction with transport.
“This is a finding which ministers will need to take account of as part of their forthcoming review of bus concessions.”