The methodology for the acquisition of proportional samples of vehicle engine exhaust gases is presented. The mini-CVS technique used is shown to correlate with full-scale CVS equipment. On the road data for regulated emissions of 15 cars are compared with an earlier survey. These data were obtained over a wide range of operating conditions including urban, rural and motorway drives. Gas chromatographic techniques have been applied to determine the emissions on the road of a range of non-regulated hydrocarbons i.e. aromatics, saturated and unsaturated species.The mini-CVS technique together with a minidilution tunnel for the determination of particulate emissions from diesel engined vehicles is described and results from light-duty and heavyduty vehicles presented.