Almost 17% of bus passengers have abandoned Brisbane’s regional bus companies and returned to their cars, figures show.

Rail Back on Track says the drop showed passengers were shunning out-of-date connections between regional bus lines because they "did not begin earlier enough or run late enough".

By contrast, Brisbane City Council’s bus lines show an overall passenger drop of 3.8 per cent. The Queensland government continues to invest in public transport and create initiatives to encourage greater use.