Presumably this could be measured. Although attitude may not be measurable at the time it woould surely be possible to measure traffic speed (as it varies en masse or for an individual vehicle) and measure the inter vehicle gaps.

I measured on any busy road (no need to apply speed change orders) the relationships should become clear. Exclude HGV's on Motorways though as they nearly always slipstream with negligible gaps.

This way the theory could be proved to make a stronger (or maybe weaker?) arguement. Gap relative to speed between vehicles moving at the same speed perhaps?

Obviously there could be some anomalies ....

The human animal is a risk taker, always has been, always will be. Increasing the level of safety in one area will invoke an increase of risk in another. For this reason ABS brakes do not reduce the number of rear-end accidents because people feel safe driving
closer than they would without ABS. Death rates FOR DRIVERS following the compulsory introduction of seatbelts did indeed reduce but the death rate for pedestrians and 2 wheel riders increased to more than cover the reduction, the risk had shifted
to another area. There would be no need to actively promote "Keep your distance" if seatbelts were illegal and 4" spikes in the middle of the steering wheel made compulsory!