Denver Police
(Traffic Enforcement)
Relevant law:
• Colorado law explicitly prohibits modifying a vehicle to be louder than its original factory muffler (CRS 42-4-225)
What it means:
• Vehicles cannot legally be modified to produce more noise than stock
Why it’s not enforced:
→ The original factory sound level is not defined in a usable way
→ Officers would need specialized sound measurement procedures
→ There is no practical way to consistently measure violations during normal traffic stops
Denver Department of Public Health & Environment (DDPHE)
Relevant standard:
-
Vehicle noise enforcement is tied to federal testing procedures (40 CFR §205.54)
-
Based on a controlled low-speed pass-by test (~83 dB standard)
What it means:
-
Noise must be measured under specific, controlled conditions
Why it’s not enforced:
→ The test requires controlled speed, distance, and environment
→ Cannot be realistically performed on active city streets
→ Makes real-world enforcement impractical
Department of Excise & Licenses
Relevant rule:
-
Denver regulates licensed auto shops under DRMC Article VIII (Garages)
What it means:
-
Shops must be licensed and follow city business rules
Why it’s not enforced:
→ The code does not clearly prohibit installing loud exhaust systems (the at-fault party is the vehicle owner and not the shop)
→ Limited authority to act on vehicle noise modifications
→ Enforcement is focused on licensing, not vehicle compliance
311 / City Reporting System
What exists:
-
Residents can submit general noise or non-emergency complaints
What’s missing:
-
No dedicated category for vehicle noise
-
No clear intake for speeding or racing patterns
-
No system to track or map these reports over time
-
These issues are underreported, inconsistently tracked, and difficult to act on
Denver Municipal Code (General Noise / Disturbance)
Relevant law:
-
Denver prohibits disturbing the peace through unreasonable noise (DRMC 38-89)
-
Also requires vehicles to have mufflers preventing excessive noise (DRMC 54-74)
What it means:
-
Excessive vehicle noise is already illegal under city law
Why it’s not enforced:
→ Relies on subjective judgment (“unreasonable noise”)
→ Difficult to prove consistently without objective measurement
→ Not designed for high-frequency, mobile violations like traffic
The result
Existing laws prohibit excessive vehicle noise—but rely on:
-
a “no louder than stock” standard that cannot be practically measured, or
-
testing methods that cannot be used in real-world conditions
No single agency has both the authority and the tools to enforce these laws on the street.