The Taxpayers' Alliance says more coaches should be way forward rather than the HS2 rail link, which would speed up journeys between London and the North.
Matthew Sinclair, Chief Executive of the TaxPayers' Alliance, said:
"As the projected costs have increased dramatically, the already fragile case for HS2 has completely disintegrated.
"There are far cheaper and better ways of substantially increasing capacity much more quickly on the route, not least by reducing the number of first class carriages and lengthening the trains."
More top news
Variable cloud, warmer air & mainly dry outlook over the next few days. Some potential rain Sunday night into Monday. Kerrie has the detail
Higher temperatures and more sunshine than average - but a very dry April this year
A breast surgeon from Cheshire has been convicted of wounding with intent after carrying out "completely unnecessary" operations.