A system comprising: (i) a vehicular compression ignition engine comprising one or more engine cylinders and one or more electronically-controlled fuel injectors therefor; (ii) an exhaust line for the engine comprising: a first emissions control device comprising a first honeycomb substrate, which comprises a hydrocarbon adsorbent component; a second emissions control device comprising an electrically heatable element and a catalysed second honeycomb substrate, which comprises a rhodium-free platinum group metal comprising platinum, wherein the electrically heatable element is disposed upstream from the catalysed second honeycomb substrate and wherein both the electrically heatable element and the catalysed second honeycomb substrate are disposed downstream from the first honeycomb substrate; a third emissions control device, which is a third honeycomb substrate comprising an ammonia-selective catalytic reduction catalyst disposed downstream from the second emissions control device; a source of nitrogenous reductant and/or a precursor thereof and an injector for injecting nitrogenous reductant and/or a precursor therefor into an exhaust gas flowing in the exhaust line downstream of the catalysed second honeycomb substrate and upstream of the third honeycomb substrate; and one or more temperature sensors located: upstream of the electrically heatable element and/or upstream of the first honeycomb substrate; and between the electrically heatable element and the catalysed second honeycomb substrate; and (iii) an engine control unit comprising a central processing unit pre-programmed, when in use, to control both a heating activation state of the electrically heatable element; and an injection timing strategy of the one or more electronically-controlled fuel injector to increase the temperature of at least the first emissions control device following key-on/cold-starting a vehicle comprising the system, wherein the one or more temperature sensors are electrically connected to the engine control unit for feedback control in the system, wherein dosing of the nitrogenous reductant or precursor thereof is controlled by the pre-programmed central processing unit. (i) a vehicular compression ignition engine comprising one or more engine cylinders and one or more electronically-controlled fuel injectors therefor; (ii) an exhaust line for the engine comprising: a first emissions control device comprising a first honeycomb substrate, which comprises a hydrocarbon adsorbent component; a second emissions control device comprising an electrically heatable element and a catalysed second honeycomb substrate, which comprises a rhodium-free platinum group metal comprising platinum, wherein the electrically heatable element is disposed upstream from the catalysed second honeycomb substrate and wherein both the electrically heatable element and the catalysed second honeycomb substrate are disposed downstream from the first honeycomb substrate; a third emissions control device, which is a third honeycomb substrate comprising an ammonia-selective catalytic reduction catalyst disposed downstream from the second emissions control device; a source of nitrogenous reductant and/or a precursor thereof and an injector for injecting nitrogenous reductant and/or a precursor therefor into an exhaust gas flowing in the exhaust line downstream of the catalysed second honeycomb substrate and upstream of the third honeycomb substrate; and one or more temperature sensors located: upstream of the electrically heatable element and/or upstream of the first honeycomb substrate; and between the electrically heatable element and the catalysed second honeycomb substrate; and a first emissions control device comprising a first honeycomb substrate, which comprises a hydrocarbon adsorbent component; a second emissions control device comprising an electrically heatable element and a catalysed second honeycomb substrate, which comprises a rhodium-free platinum group metal comprising platinum, wherein the electrically heatable element is disposed upstream from the catalysed second honeycomb substrate and wherein both the electrically heatable element and the catalysed second honeycomb substrate are disposed downstream from the first honeycomb substrate; a third emissions control device, which is a third honeycomb substrate comprising an ammonia-selective catalytic reduction catalyst disposed downstream from the second emissions control device; a source of nitrogenous reductant and/or a precursor thereof and an injector for injecting nitrogenous reductant and/or a precursor therefor into an exhaust gas flowing in the exhaust line downstream of the catalysed second honeycomb substrate and upstream of the third honeycomb substrate; and one or more temperature sensors located: upstream of the electrically heatable element and/or upstream of the first honeycomb substrate; and between the electrically heatable element and the catalysed second honeycomb substrate; and (iii) an engine control unit comprising a central processing unit pre-programmed, when in use, to control both a heating activation state of the electrically heatable element; and an injection timing strategy of the one or more electronically-controlled fuel injector to increase the temperature of at least the first emissions control device following key-on/cold-starting a vehicle comprising the system, wherein the one or more temperature sensors are electrically connected to the engine control unit for feedback control in the system, wherein dosing of the nitrogenous reductant or precursor thereof is controlled by the pre-programmed central processing unit.