Diesel and RDE2 Standards

RDE vs RDE2: How Diesel Emissions Standards Impact Your Road Tax

March 10, 2024•6 min read

Understanding RDE and RDE2 Standards

The evolution from RDE (Real Driving Emissions) to RDE2 represents a significant advancement in how diesel vehicle emissions are tested and regulated. This comparison guide explains the key differences and their impact on your vehicle tax.

Key Difference

While both standards test emissions in real-world conditions, RDE2 introduces stricter NOx limits and has direct implications for vehicle taxation.

Key Differences Between RDE and RDE2

Testing Procedures

RDE: Initial real-world testing protocol
RDE2: Enhanced testing with stricter parameters
Different conformity factors for NOx emissions
Expanded testing conditions and scenarios

Emissions Limits

RDE: Higher conformity factor for NOx
RDE2: Stricter NOx limits (conformity factor of 1.43)
Different temperature and altitude requirements
Enhanced cold start emissions monitoring

Tax Implications

The choice between RDE and RDE2 compliant vehicles has significant tax implications:

RDE Vehicles

Subject to diesel supplement on first-year tax
Higher first-year tax rates
May face restrictions in certain clean air zones

RDE2 Vehicles

Exempt from diesel supplement
Lower first-year tax rates
Better future-proofing against emissions regulations

Important Consideration

When buying a diesel vehicle, the difference in first-year tax between RDE and RDE2 compliant vehicles can be substantial - potentially saving hundreds of pounds.

Implementation Timeline

Understanding when these standards were introduced helps identify vehicle compliance:

RDE: Introduced September 2017
RDE2: Mandatory for new type approvals from January 2020
RDE2: Required for all new registrations from January 2021

Practical Implications

The differences between RDE and RDE2 affect various aspects of vehicle ownership:

Purchase costs and tax implications
Environmental impact and emissions
Resale value considerations
Clean air zone compliance

Choosing Between RDE and RDE2

When deciding between an RDE or RDE2 compliant vehicle, consider:

Initial purchase price differences
First-year tax savings with RDE2
Long-term environmental regulations
Intended use and driving locations

Conclusion

While both RDE and RDE2 represent improvements in emissions testing, RDE2 compliance offers clear advantages in terms of tax savings and future-proofing. When purchasing a diesel vehicle, the tax benefits of RDE2 compliance should be a key consideration.

To calculate the exact tax difference between RDE and RDE2 vehicles, use our free car tax calculator.

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