If the fuel that goes in car engines is extracted from hydrocarbons, which consist of only Hydrogen and Carbon, and those hydrocarbons react with Oxygen in the air (combustion reaction), to produce CO2 and H2O, why do we get a bad smell from car exhaust fumes if both gases are odorless? Submitted by Protoflare t3_11ck5es on February 26, 2023 at 3:38 PM in askscience 47 comments 336