Road transportation has received the attention of researchers due to its higher carbon footprint. Alternative fuels present major advantages in terms of environmental sustainability. For this reason, an enviro-economic analysis of alternative fuels carries great significance. However, scarce attempts have been rendered in order to ascertain the impact of a hydroxy gas (HHO) and compressed natural gas (CNG) mixture on sustainable environmental development. The current study addresses this issue by employing an HHO–CNG mixture and gasoline in spark ignition (SI) engines for the purposes of performance and environmental pollutants measurement. Then, engine emission data were substituted for Weibull distribution in order to establish suitability for 50 and 95% confidence intervals (CIs). The mixture outperformed gasoline in terms of brake-specific fuel consumption (BSFC) and emission contents. On average, hydroxy gas with CNG produced 10.59% lower oxides of nitrogen (NO_X) comparative to gasoline. Finally, the enviro-economic analysis also turned out to be in favor of the hydroxy gas mixture owing to a saving of 36.14% in USD/year due to 27.87% lower production of carbon dioxide (CO₂) emission.

Methanol showed promising results as an alternative to gasoline fuel. However, there exists a research gap for the effect of oxygenated fuel on lubricant oil deterioration along-with engine performance and emissions. This study aims the very topic. The characteristics of SI engine were evaluated for two different loads and nine different engine speeds. The lubricant oil samples were taken out from engine oil sump after 100 h of engine operations using gasoline (G) and M12 sequentially. The brake power of M12 was observed higher in comparison with G. The maximum BTE of 23.69% was observed for M12 on lower load and 2800 rpm. On average, the 6.05% and 6.31% decrease in HC emissions were observed using M12 in comparison with G at lower and higher load respectively. M12 produced 32.52% higher NOx emissions than that of G at lower load. The reduction in kinematic viscosities at 40°C of lubricant oil were found 11.61% and 18.78% for M12 and G respectively. TAN, specific gravity, flash point and ash content of lubricant oil were observed 10.23%, 0.079%, 5.81% and 0.97% higher for M12 respectively. The lubricant oil composition could be developed in future for such fuels which may prolong its life cycle.

Growing environmental concerns over global warming and depleting fossil fuel reserves are compelling researchers to investigate green fuels such as alcoholic fuels that not only show the concrete decrement in emissions but also enhance engine performance. The current study emphasizes the influence of different alcoholic fuel blends in gasoline on engine performance and emissions for an engine speed ranging from 1200 to 4400 rpm. The obtained performance results demonstrate that the brake power and brake thermal efficiency (BTE) increased with an incrementing blend percentage of ethanol and methanol in gasoline (EM). The minimum brake specific fuel consumption (BSFC) was ascertained using pure gasoline followed by E2 and then E5M5. The NO_x and CO₂ emissions can be described in the decreasing order of E, EM and gasoline due to same trend of exhaust gas temperature (EGT). CO results were in reverse order of CO₂. HC emissions were found in the increasing order of E, EM and pure gasoline. E10 performed better among all blends in terms of less exhaust emissions and engine performance. However, EM blended with gasoline significantly reduced NO_x. E5M5 produced 1.9% lower NO_x emission compared to E10 owing to 1.2% lower EGT. Moreover, greenhouse gases such as CO₂, which is mainly responsible for global warming reducing by 1.1% in case E5M5 as compared to E10.

The quest for alternatives to gasoline becomes more urgent day by day because of environmental concerns and exhaustion of fossil fuel reserves. Methanol has proved to be an attractive renewable, alternative fuel due to improvement in engine performance. This research not only addresses performance and emissions from engine but also examines the importance of lubricant oil in engine by monitoring variation in physicochemical properties after 100 hours of operations on gasoline with octane rating 92 (G-92) and also 6% methanol by volume blended with 94% gasoline by volume (M-6). The performance and emission parameters were evaluated for nine different speeds. The accuracy of emission data was then calculated using Weibull distribution within 75% and 95% confidence intervals. On average, M-6 produced 3.72% more brake power than G-92. But M-6 produced 3.40% lower HC emission, and 5.54% lower CO emission in comparison with G-92. The lubricant oil exhibited 4.76%, 1.28%, 6.03%, 0.48%, 0.045%, and 3.49% rise in (KV)_40°C, (KV)_100°C, TAN, ash content, specific gravity, and flashpoint for M-6, respectively. Although M-6 improves engine performance and reduces carbon emissions, it is also responsible for early degradation of lubricant oil. Therefore, efforts for reducing the degradation rate of lubricant oil will open new avenues for future research.