When you do stills then it might be an option to do that in postwork. Photoshop for example. Good control and exactly as you want it. Select an area and say "motion blur please". The "please" is important of course - otherwise you have to do it manually! To make it easier you can render objects separately with mask and combine those in Photoshop. Only another option.

One day your ship comes in - but you're at the airport.