Hundreds of bikers have gathered to ride in memory of Harry Dunn, the teenager whose crash death led to a diplomatic row with the US.
Harry, 19, died after the collision in Northamptonshire in August that led to suspect Anne Sacoolas leaving the UK claiming diplomatic immunity.
A file has been passed to prosecutors, but no charges have been brought.
Mr Dunn's mother Charlotte Charles said support from the public was "the only thing keeping us going".
Harry's father Tim said the support from those who took part in the motorbike and scooter ride, which started in Brackley, Northamptonshire, was "fantastic".
Talking to Sky News, Mrs Charles said decisions in the case by the Crown Prosecution Service were "taking too long".
"The case is a pretty clear cut, we are just waiting on their decision," she added.
Harry was fatally injured on 27 August, when his motorbike was in collision with a car owned by Mrs Sacoolas, 42, outside RAF Croughton, where her husband Jonathan was an intelligence officer.
Mr Dunn, who explained the family was "struggling", said: "We are getting more frustrated by the delays and the authorities."
Mrs Sacoolas left the UK claiming diplomatic immunity, but was interviewed by Northamptonshire Police in the US last month.
Earlier this week, former US Secretary of State Hillary Clinton said the rules around diplomatic immunity "should be looked at".
Mrs Clinton also said a meeting at the White House between Harry's family and President Trump, where Mrs Sacoolas was in the next room, had been "clumsy and heavy-handed".
Mr Dunn said his hoped Mrs Clinton's comments would "help push forward" the chance of Mrs Sacoolas return to the UK.