While intake air heating is a widespread technology used in heavy duty diesel engines, it rarely appears in the field of HSDI diesel engines. Nevertheless, intake air heating is currently under study as a possible alternative to glow plugs for cold start assistance in HSDI diesel engines. Since the use of intake air heaters involves a cylinder-head simplification, this solution presents both economical and combustion advantages. Despite of the negative impact of the high intake temperatures on NO, emissions, intake air heating reduces significantly HC and CO emissions during warm up due to combustion improvement. While the potential of intake air heating technology to assist cold start is proved, the present paper is devoted to the evaluation of the intake air heating technology potential to reduce pollutant emissions from Diesel combustion. To deal with this objective a deep analysis of both glow plug and intake air heating technology behaviour during the MVEG-A cycle is done. Experimental tests are carried out on a small turbocharged direct injection Diesel engine in an engine-in-the-loop (EIL) approach. Results prove that an optimal intake air heating strategy together with an adapted air loop control calibration can improve HC, CO and NO, emissions with only a scarce PM increase. (c) 2008 Elsevier Ltd. All rights reserved.