In dynamometer vehicle testing, on-board diagnostics (OBD) signals are used to monitor vehicle parameters. Combining OBD data with PTR-MS measurements of a variety of emitted VOCs such as acrolein, ethanol, styrene, formaldehyde, acetone, ethylbenzene, benzene, acetaldehyde, xylene, trimethylbenzene, 1,3-butadiene, toluene, and naphthalene makes correlation studies possible.
Matsunaga et al.  also studied the emissions from gasoline vehicles and found that the VOC emissions from unburned fuel are extremely high at the beginning of a cold-start drive cycle but quickly vanish as the vehicle warms up. The PTR-MS is unique with the ability to quantify multiple VOC species in real-time.
Gasoline/Petrol and ethanol blends
Gasoline is often blended with ethanol, such as E10 (10% ethanol in 90% gasoline), which has economic as well as environmental considerations. Impacts of ethanol/gasoline ratio on emissions are actively studied elsewhere. For such analysis, a real-time instrument like a PTR-MS is a powerful tool for revealing the relationship between emissions and vehicle parameters.
 Matsunaga et al. (February, 2015): Motor Vehicle Exhaust Analysis with a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) – Comparison Study with Conventional Methods for BTEX and Other Toxic Air Contaminants. Poster presented at CRC Mobile Source Air Toxics Workshop, Sacramento, CA, U.S.A.