06/09/2009
- Understanding Emissions Testing for Hybrid Vehicles
- The Rise of Hybrid Technology and Emissions Concerns
- Green NCAP: A New Standard in Environmental Testing
- The Mitsubishi Outlander PHEV: A Case Study
- Best and Worst Performers Across Categories
- Innovative and Alternative Powertrains
- The Importance of Optimal Usage for PHEVs
- Conclusion: Are Hybrids Tested for Emissions?
- Frequently Asked Questions
Understanding Emissions Testing for Hybrid Vehicles
The world of automotive technology is constantly evolving, with hybrid vehicles increasingly becoming a popular choice for consumers looking to reduce their environmental impact and fuel costs. However, a common question that arises is whether these innovative cars, particularly plug-in hybrids (PHEVs), are subject to the same rigorous emissions testing as their traditional petrol and diesel counterparts. The answer is nuanced, and understanding the testing procedures and their real-world implications is crucial for making informed purchasing decisions. This article delves into the intricacies of emissions testing for hybrid vehicles, examining the role of organisations like Green NCAP and what their findings reveal about the environmental performance of these cars.
The Rise of Hybrid Technology and Emissions Concerns
Hybrid vehicles, by their very nature, combine internal combustion engines with electric motors, aiming to improve fuel efficiency and lower emissions. Plug-in hybrids, in particular, offer the ability to run on electric power alone for a significant range, with the petrol engine acting as a backup or for longer journeys. This dual-powertrain system has led to favourable tax implications and marketing claims of superior environmental performance. However, independent testing organisations are shedding light on the actual real-world emissions of these vehicles, revealing that the benefits are not always as straightforward as they might seem.
Green NCAP: A New Standard in Environmental Testing
Green NCAP is a new initiative, partly funded by Which?, that aims to provide independent ratings on the environmental impact of cars. Much like Euro NCAP focuses on safety through crash tests, Green NCAP employs a combination of lab tests and road tests to assess a vehicle's environmental credentials. These tests are designed to be more realistic than official type-approval tests, often conducted at lower ambient temperatures (around 14°C compared to the official 23°C) and incorporating on-road driving assessments that go beyond standard requirements. Green NCAP's methodology evaluates three key areas:
- Clean Air assessments: These checks focus on harmful pollutants like Nitrogen Oxides (NOx), which contribute to urban air pollution.
- Energy Efficiency: This measures how much energy is wasted during the driving process, reflecting the overall efficiency of the powertrain.
- Greenhouse Gas test: This rates the release of gases that contribute to climate change, primarily Carbon Dioxide (CO2).
The Mitsubishi Outlander PHEV: A Case Study
The Mitsubishi Outlander PHEV has been a significant success in the market, largely due to its low CO2 emissions in official tests, which translate into lower car tax (Vehicle Excise Duty or VED) and company car tax rates. However, Green NCAP's independent tests painted a different picture. The popular plug-in hybrid SUV received only a two-star rating out of five, indicating that it is not one of the most environmentally friendly cars available. This finding highlighted a critical point: buying a plug-in hybrid does not automatically guarantee a cleaner car than some modern petrol or diesel vehicles.
Green NCAP's report suggested that the real-world performance of PHEVs could be worse than their test results imply. This is primarily because their tests assume journeys begin with a full battery and end with an empty one. In reality, Green NCAP states that drivers 'only rarely' operate their PHEVs optimally, with many predominantly using the combustion engine. When a PHEV is primarily driven by its petrol engine while also carrying the weight of a flat battery, its fuel economy can indeed be inferior to that of the most efficient new petrol and diesel cars.
Best and Worst Performers Across Categories
Green NCAP's latest tests covered a range of vehicle types, from plug-in hybrids and SUVs to medium and small family cars. Here's a summary of some of the key findings:
Plug-in Hybrid Cars
| Vehicle | Green NCAP Rating | Key Observations |
|---|---|---|
| Toyota Prius Plug-In Hybrid | 4 stars | Strong performance across all three test areas. Toyota's expertise in hybrid technology is evident. A gasoline particulate filter has since been added to improve performance further. |
| Mitsubishi Outlander PHEV (2.4) | 2 stars | Scored below average, with "weak" CO2 emissions in cold and warm-start tests. Performance can be similar to petrol/diesel cars if not driven optimally on electric power. |
| Kia Niro (1.6 GDI) | 3.5 stars | A competitive performer in the PHEV segment. |
SUVs (Petrol, Diesel, or Mild Hybrid)
| Vehicle | Green NCAP Rating | Key Observations |
|---|---|---|
| Ford Kuga (2.0 EcoBlue Hybrid) | 2.5 stars | The best performer in the SUV category, demonstrating the potential of mild hybrid technology. However, it showed high emissions of N2O (nitrous oxide), a potent greenhouse gas. |
| Land Rover Discovery Sport (D180) | 1.5 stars | Joint last in the SUV rankings. Performed poorly in energy efficiency and greenhouse gas emissions, with high CO2 and N2O. Its weight also impacted efficiency. |
| Hyundai Tucson (1.6 GDI) | 1.5 stars | Joint last in the SUV rankings, indicating significant room for environmental improvement. |
| Volvo XC60 (D4) | 2 stars | A respectable score for a diesel SUV, but still below average for overall environmental performance. |
| BMW X1 (18d xdrive Automatic) | 2 stars | Similar performance to the Volvo XC60, highlighting the challenges for diesel SUVs in meeting stringent environmental targets. |
Medium Cars
| Vehicle | Green NCAP Rating | Key Observations |
|---|---|---|
| Volkswagen Golf (1.5 TSI) | 3.5 stars | Achieved a strong score for a non-electrified car, performing well in air pollution and energy efficiency, with good greenhouse gas ratings. |
| Honda Civic (1.0 Turbo) | 2.5 stars | Scored below par in air pollution and greenhouse gas emissions, with high carbon monoxide and ammonia, and "weak" CO2 emissions. |
| Audi A3 (1.5 TSI) | 3 stars | A solid performer, demonstrating good efficiency and emission control for a petrol engine. |
| Seat Leon (2.0 TDI) | 3 stars | A good result for a diesel, showing that well-engineered diesel engines can still offer competitive environmental performance. |
| BMW 1 Series (118i) | 2.5 stars | A moderate score, suggesting that while it offers decent performance, its environmental impact could be improved. |
| Mercedes-Benz A-Class (180d) | 2.5 stars | Similar to the BMW 1 Series, this diesel offering shows average environmental performance. |
Small Family Cars
| Vehicle | Green NCAP Rating | Key Observations |
|---|---|---|
| Toyota Yaris (1.5 Hybrid) | 3.5 stars | Excellent fuel economy and strong performance across all test areas, reinforcing Toyota's hybrid leadership. |
| Mini Hatch (Cooper Steptronic) | 2.5 stars | An older model, scoring around four out of ten in each area. A reasonable result for a conventional petrol car, but not outstanding. |
| Citroën C3 (PureTech 82) | 3 stars | A respectable score for a small petrol car, indicating good fuel efficiency and controlled emissions. |
| Skoda Fabia (1.0 TSI) | 3 stars | Similar to the Citroën C3, the Fabia performs well in its class. |
| Dacia Sandero (SCe 75) | 2.5 stars | A budget-friendly option, but its environmental performance is average for its class. |
| Fiat Panda (1.2 8V) | 2.5 stars | Similar to the Sandero, the Panda offers affordability but average environmental credentials. |
| Vauxhall Corsa (1.2 DI Turbo) | 2.5 stars | Another car in the small family segment with average emission performance. |
Innovative and Alternative Powertrains
Green NCAP also assesses vehicles with innovative technologies aimed at improving emissions. This includes hydrogen-powered cars and all-electric vehicles (EVs). The Hyundai Nexo, a hydrogen fuel cell car, achieved a perfect 5-star rating, highlighting the potential of this technology for zero tailpipe emissions. Similarly, the Volkswagen ID.3 (58 kWh), an all-electric car, also received a 5-star rating, demonstrating the significant environmental advantages of pure electric driving.
The Mazda CX-30, featuring Mazda's SkyActiv-X technology which aims to improve petrol engine efficiency, scored 2.5 stars. While innovative, this suggests that even advanced petrol engine technologies still face challenges in matching the environmental performance of electrified or zero-emission vehicles.
The Importance of Optimal Usage for PHEVs
The findings from Green NCAP underscore a crucial point for plug-in hybrid owners: the environmental benefits are heavily dependent on how the car is used. To maximise the advantages of a PHEV, regular charging and consistent driving on electric power are paramount. When a PHEV is frequently driven using only its internal combustion engine, especially if it's carrying the added weight of a depleted battery, its fuel consumption and emissions can be significantly higher than expected. This can negate the perceived environmental advantage over a modern, efficient petrol or diesel car.
Manufacturers often promote PHEVs based on their low official CO2 figures, which are typically achieved under ideal testing conditions that favour electric-only driving. However, real-world usage patterns, which Green NCAP's tests aim to simulate more closely, can reveal a different story. Therefore, potential buyers should consider their typical driving habits and charging availability when choosing a PHEV.
Conclusion: Are Hybrids Tested for Emissions?
Yes, hybrid vehicles, including plug-in hybrids, are subject to emissions testing. While official tests determine tax bands and regulatory compliance, independent bodies like Green NCAP provide a more comprehensive and realistic assessment of their environmental impact. The results from Green NCAP suggest that while some hybrids, like the Toyota Prius Plug-In Hybrid and Toyota Yaris Hybrid, perform commendably, others, such as the Mitsubishi Outlander PHEV, may not always deliver the environmental benefits advertised, particularly if not used optimally. For consumers, understanding these nuances and consulting independent reviews is key to making an environmentally sound choice.
Frequently Asked Questions
Do all hybrid cars need to be plugged in?
No. There are different types of hybrid vehicles. 'Self-charging' full hybrids (like the standard Toyota Prius) use their electric motor to assist the petrol engine and can capture energy through regenerative braking, but they cannot be plugged into an external power source. Plug-in hybrids (PHEVs) have a larger battery that can be charged by plugging into an electrical outlet, allowing for longer electric-only driving ranges.
Are PHEVs always better for the environment than petrol cars?
Not necessarily. While PHEVs have the potential to be significantly cleaner, especially if driven mostly on electric power and charged regularly, their real-world environmental benefit depends heavily on usage. If a PHEV is predominantly driven by its petrol engine, its fuel economy and emissions can be worse than a highly efficient modern petrol or diesel car.
What does Green NCAP test for?
Green NCAP tests for three main areas: Clean Air (pollutants like NOx), Energy Efficiency (how much energy is wasted), and Greenhouse Gases (like CO2). They use a combination of lab and road tests designed to reflect more realistic driving conditions than official type-approval tests.
Why did the Mitsubishi Outlander PHEV score poorly?
The Mitsubishi Outlander PHEV received a low score from Green NCAP because its emissions performance, particularly CO2, was found to be weaker in more realistic testing conditions compared to official tests. This suggests that its environmental advantage is highly dependent on consistent charging and electric-only driving, which many users do not achieve.
Are electric cars always the greenest option?
Based on current testing by organisations like Green NCAP, all-electric vehicles (EVs) generally achieve the highest environmental ratings. This is because they produce zero tailpipe emissions. However, the overall environmental impact of an EV also depends on how the electricity used to charge it is generated.
If you want to read more articles similar to Do Hybrids Need Emissions Testing?, you can visit the Emissions category.