MythBusters · Video summary

Are Home-Built Contraptions More Dangerous Than They Look? | MythBusters | S5 E29 | Full Episode

MythBusters reveals that clean cars are more fuel-efficient than dirty ones, and surprisingly, dimpling a car improves its aerodynamics and fuel economy by 11%.

MythBusters · March 27, 2026 · 49-min episode · 6-min read

Are Home-Built Contraptions More Dangerous Than They Look? | MythBusters | S5 E29 | Full Episode

Key takeaways

🎯A dirty car is less fuel-efficient than a clean car because dirt does not create a beneficial aerodynamic effect; the clean car achieved 26.4 MPG compared to the dirty car's 24 MPG.07:12
🚀Prioritize car cleanliness for optimal fuel efficiency, as dirt negatively impacts aerodynamics.07:12
⚖️Scientific testing requires controlling variables such as food intake, time of day, and rest to ensure accurate comparisons, especially when testing physiological responses like hangovers.08:53
💡Golf ball dimples improve aerodynamics by creating a turbulent boundary layer that reduces drag and wake size, allowing them to travel further.15:51
🔬The common saying 'Stick to beer, you're in the clear. Beer and liquor, never sicker' is busted; mixing beer and liquor did not result in a worse hangover than drinking beer alone, and in some metrics, it was better.41:48
🍻Don't rely on the 'beer only is better' hangover myth; mixing drinks may not lead to a worse outcome than sticking to beer alone.41:48

Chapters

0:01🎬 Episode Introduction
1:36🛻 Myth Explanation: Dirty vs. Clean Car
2:20⛽ Testing the Dirty Car Fuel Efficiency
5:49🧼 Cleaning the Car for the Clean Test
6:34🎩 Testing with a Shiny, Clean Car
7:14🚗 Results: Dirty vs. Clean Car
8:33🍺 Myth: Alcohol and Hangovers
8:37🥂 Drinking Experiments: Beer Only vs. Beer & Spirits
20:42💧 Water Tunnel Flow Simulation
32:00🏌️‍♂️ Golf Ball Dimples on a Car
32:40🚗 Full-Scale Dimpled Car Test
42:33🤢 Hangover Test Results
46:23🚘 Fuel Efficiency of Dimpled Car
48:08🔚 Episode Conclusion and Myth Bust

The digest

This episode tests two common myths: whether a dirty car can improve fuel efficiency by mimicking a golf ball’s dimpled surface, and if mixing beer with liquor leads to worse hangovers than beer alone. Through rigorous, controlled experiments including wind tunnel testing, fuel consumption measurements, and detailed hangover symptom quantification, the MythBusters team delivers surprising insights on aerodynamics and alcohol effects, debunking and validating aspects of both myths.

High Level Overview

This episode explores the claim that a dirty car might save fuel by creating aerodynamic benefits similar to a golf ball’s dimples, and the popular belief that mixing beer with liquor causes more severe hangovers than drinking beer alone. These myths have practical implications for everyday consumers concerned with fuel costs and health after drinking. The experimenters apply methodical testing, combining real-world driving fuel measurements, fluid dynamics analysis, and tightly controlled human trials to provide evidence-based conclusions. The episode is valuable for enthusiasts of automotive efficiency, fluid mechanics, and those interested in alcohol’s physiological effects.