Over time, it has been said that a leak on the exhaust system increases the rate of fuel consumption and this claim is left without tangible investigation. This study research therefore investigates the impact of leak defect of exhaust system on the rate of fuel consumption in automobile using the exhaust system of a 1986 model of Honda Accord car as a case study. A vehicle with new exhaust pipe was used to carry out the research. During the research, the vehicle engine is allowed to work in a slow running pattern in order to keep all other factors that are affecting fuel consumption constant. Each segment of the exhaust system is detached and the effect on fuel eon consumption is noted. Similarly, a leak is made in between the segments and its effect on fuel consumption is noted. Analysis of Variance (ANOVA) was used to analyse the fuel consumption discrepancies. It is very obvious from the experiment that the each segments of the exhaust system has no effect on the fuel consumption except the muffler that has little effect because of back pressure effect which enhances fuel mileage. At the end of the experiment, it was observed that leakage in the exhaust system is also an additional factor causing excessive fuel consumption in an automobile. Therefore, the experiment showed that proper maintenance has to be done on the exhaust system to reduce fuel consumption in an automobile.