Significantly more Scots are driving alone amid rising car ownership levels and falling spending on fuel, the official Scottish Household Survey (SHS) revealed today.
Two in three cars on Scotland's roads (66 per cent) had just the driver aboard last year compared to 56 per cent two decades ago.
The rise came as the proportion of homes with cars increased from 63 to 71 per cent since 1999.
At the same time, spending on fuel has fallen, reflecting a reduction in the cost of motoring.
The monthly cost of topping up the tank has gone down from £122 in 2003 and £157 in 2011 to £112 last year.
The latest available figures for traffic on Scotland's roads, for 2017, have shown a 3 per cent increase to some 30 billion vehicle miles compared to 2016, and some 28bn in 2007 .
The statistics also revealed major social changes, with as many women as men now driving to work - 63 per cent.
The female rate has gone up from 48 per cent in 1999 and the male rate from 60 per cent.
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Working from home has also more than doubled over that period - from 7 to 16 per cent of adults.
But walking rates have fallen, from 26 to 20 per cent of journeys.
Walking to work was down from 14 to 12 per cent, and to school from 54 to 53 per cent, but cycling to school doubled from 1 to 2 per cent.
Cycling to work increased from 1.7 to 2.8 per cent.
Separate figures have already shown a decline in bus use.
Provisional estimates showed there were 377 million bus journeys in Scotland last year compared with 388m in 2017 and 471m in 2002, according to the UK Department for Transport.
The SHS showed 42 per cent of those asked had travelled by bus in the last month, a similar level to 2002, but apparently less frequently.
By contrast, the proportion taking the train in the last month has doubled since 1999 from 15 to 31 per cent.
Total ScotRail passengers were up from 57m to 98m since 2002.
Scots also flew more for leisure over the last decade - up from 47 to 51 per cent of adults.
The survey also showed a fall in satisfaction with public transport from 75 per cent in 2014 to 65 per cent in 2018, the lowest since 2007.
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Scottish Conservatives transport spokesman Jamie Greene said: “Far from promoting environmentally-friendly transportation, the trend is going in the opposite direction with fewer people making journeys on foot and we’ve seen single-occupant car journeys on the rise.
“Unless we have accessible public transport options that are frequent and reliable, we will not meet our goals of reducing transport emissions, which currently account for a third of Scotland’s carbon output.
“The Scottish Government must improve on getting the basics right and better prioritise investment if it wants to encourage people out of cars and onto public transport."
Colin Howden, director of sustainable transport campaigners Transform Scotland, said: “Today’s new statistics come as no surprise - we’re paying the price for a decade where the bulk of new capital spending has gone into new trunk roads rather than investing in local transport such as walking, cycling and buses.
“Despite last week’s welcome announcement of £500m investment in bus services announced as part of the Programme for Government, Scottish ministers’ expenditure plans remain grotesquely skewed towards supporting more car use, with £6bn devoted to just two roads, the A9 and A96 dualling projects.
“There is no reason why Scotland shouldn’t be performing better on sustainable transport.
Today’s figures show the majority of all journeys are short in distance, the type where many more should be made on foot, by bike and by bus.”
Scottish Labour transport spokesman Colin Smyth said: "It’s no wonder the public are not happy with the public transport they use, it is being mismanaged under the SNP.
“Rail commuters have had to endure a rip-off fare rise whilst their services have been routinely delayed, overcrowded or cancelled.
“Meanwhile those who rely on buses have had routes cut and fares soar in recent years.
“Enough is enough.
“Labour will transform our transport system by bringing our railways into public ownership and introducing free bus travel for everyone aged under 25.”
Scottish Greens transport spokesman John Finnie said: “These figures show the need for more ambition in tackling the climate emergency, as the Scottish Greens have called for.
“Transport is a major factor in Scotland missing its emissions targets last year.
"Meanwhile, there are dangerously high levels of air pollution in our cities from our roads.
“The Scottish Government’s programme for the year did not go far enough.
"The electrification of northern train routes is basic infrastructure upgrade, and more money for bus lanes just won’t cut it when satisfaction in public transport is in decline.
“Meanwhile, the budget to support cycling and walking has been frozen.
“Scotland needs a publicly-owned integrated transport network, like we propose in our Scottish Green New Deal, so people have better options than driving to work alone in a polluting vehicle.
"That means free bus travel, nationalised railways and proper support for walking and cycling.”
Scottish Liberal Democrat transport spokesman Mike Rumbles said: “If the government is serious about the climate emergency then it needs to shift its transport plans up a gear.
"It must make preparations now to put Scotrail into new hands, deliver on its many promises on ferries and act on my call - backed by Parliament - for every schoolchild to have the opportunity to benefit from cycle training.”
A spokesperson for the Scottish Government's Transport Scotland agency said: “We are committed to delivering a sustainable, accessible and fairer transport system as outlined in our draft national transport strategy.
"More than £1 billion is being invested each year in public and sustainable transport, encouraging people to use public transport and active travel modes.
“The strategy also sets out how future transport investment decisions will be made in line with the sustainable travel hierarchy, which prioritises walking, cycling and public and shared transport options in preference to single occupancy private car.
“Last week’s Programme for Government set out a step change in investment for bus of over £500m to improve bus priority infrastructure to reduce the impacts of congestion on bus services and get more people to make sustainable multi-modal journeys.
"Almost two thirds of passengers are very or fairly satisfied with public transport services but we recognise that there is more work to be done by our delivery partners to help address a decline in this area over the last few years."