Could you live without a car?
Reya El-Salahi from London asked herself this question when she moved into a car-free development, but over the past year she's been fine.
Lil Boyer from Dorset says she can't use rural buses because they are "rubbish" - but she's embarrassed to drive so much.
They are part of a trend of young people going cool on the car.
In the 1990s, 80% of people were driving by 30; now this marker is only reached by 45.
Men under 30 are travelling only half the miles their fathers did.
The Commission on Travel Demand says this should lead to a government re-think about travel priorities.
It points out that people in general are driving much less than expected:
- People are travelling 10% fewer miles than in 2002 and spending 22 hours less travelling each year than a decade ago.
- There has been a 20% reduction in commuter trips per week since the mid 1990s
- Growth in car traffic has slowed. In the 1980s, it grew by 50% whereas in the decade to 2016 it grew by 2%
Yet BBC News has learned that next week the government is likely to forecast a rise in traffic of between 20% and 60% by 2040.
It will predict that, collectively, drivers will be doing up to 400 billion miles a year.
That, in turn, will increase pressure for more spending on roads.
So will driving increase or not?
It depends on how much you believe the government's traffic forecasts. A spokesman said the planners had registered the changes in travel habits in its three-yearly forecast of future traffic.
But the Commission says the forecast is a huge overestimate that will lead to a boom in controversial road-building. It says the forecasters have not properly taken into account that people generally are driving much less.
The commission's chair, professor Greg Marsden, told the BBC: "We need root and branch reform of traffic forecasting.
"Forecasts of future demand for future road use are highly debatable because they appear to be based on the sort of traffic growth we saw in the 1990s. We don't have those levels of traffic growth any more."
"Many young people are happy to live their lives without a car - especially in big cities where public transport is good."
Why does it matter?
The Commission says that unless ministers radically re-think the way they plan transport infrastructure, they will be spending taxpayers' money on the wrong things.
They say that instead of estimating future demand for driving, then building roads to meet the demand, ministers should be asking how people want to live - then planning transport solutions accordingly.
What would that mean for people?
It could mean more investment in public transport, walking and cycling provision in cities where many young people prefer to live without owning a car. This would reduce pollution too, and help combat climate change.
Different solutions would be needed in rural areas where good public transport is scarce and where most people are dependent on cars.
What is the Commission?
The Commission on Travel Demand is an independent group of academic experts on travel forecasting. It's funded by the government-backed Research Councils UK.
Prof Marsden told us government planners are in danger of locking the UK into a high-traffic future by providing extra road space that will simply encourage more traffic growth.
What is the key message?
The report says: "We've got to join the dots on policy and see that more active forms of transport like walking and cycling are going to improve people's health and combat the obesity epidemic. Walking and cycling have a vital role to play, yet they appear to be the Cinderellas of transport."
Why is travel demand changing?
Prof Marsden's group says: "There is a combination of longer-term societal shifts in activities such as how we work and how we shop, changing demographics, shifts in income across the population as well as policies in the transport sector which have encouraged urbanisation.
"The recession has played a part - as has the shift to mobile internet and other advances in information and communication technologies. However, the trends predate both of these."
Other contributory factors in a complicated equation might be high car insurance for young men in particular, and the growth in taxi services like Uber.
In some cities, housing developments are car-free. Reya El-Salahi from London told us: "In order to live in my home you have to sign a contract that you won't apply for a parking permit. I've driven since I was a teenager and it's something I was worried about. But it's been absolutely fine. Surprisingly."
Are travel habits in the countryside changing too?
Yes but to a lesser extent. A car is still needed for many in rural areas. Take Lil Boyer, an occupational therapist and young mum from Wimborne in Dorset. She told us: "I have tried getting the bus to work but if you miss your bus you are stranded and I can't get home to my daughter.
"I feel guilty about the amount I use the car but it's not really an option".
What are other countries doing about it?
The report says across Europe, cities have seized on the trend of falling trip rates. They are proactively planning to increase their populations whilst reducing or holding steady car traffic.
Rather than debating what future demand might be, they are setting out a vision for their cities and then thinking about the role of vehicles in that.
The Commission says in the UK, London and Greater Manchester are leading the way in planning cities where people can walk, cycle and use public transport and taxis - without needing to own a car.
What does the government say?
A spokesman said: "Good transport infrastructure is key to a thriving economy which is why we are making significant investments to transform our transport network, helping create jobs and boost economic growth.
"We regularly update our forecasts and evidence base, keeping them up-to-date for planning future transport investment. We are working closely with industry and consumers to ensure we are prepared for the transport network of the future."
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