This is a result of ELS because when you goto pull them over they might hit something or hit the gas if you hit the horn. I've noticed that to happen when i hit the horn. If you download Albos Traffic Policer it will give you the option to allow the vehicle you've pulled over to mimic you and move to where you want to go if you hit CTRL+Q
http://www.lcpdfr.com/files/file/8303-traffic-policer-road-signs-traffic-offences-breathalyzer-speed-checker-doorlock-drugalyzer-ambient-events-traffic-offences-traffic-callouts-traffic-stop-assist-mimic-more/
Hope this helps,
JP