Diesel scores 0.00 opacity at Spain's MOT test again
Can a diesel really hit 0.00 opacity at the Spanish ITV roadworthiness test? Plenty of motorway driving and quality fuel can make all the difference, according to real-world experiences.
English · Original discussion in Spanish · Published
How to get 0.00 opacity at the ITV test with a 15-year-old diesel
A diesel BMW with 205,000 km on the clock has passed every ITV roadworthiness test with 0.00 opacity, except once when it ran on adulterated fuel. The recipe: premium diesel, motorway driving and a healthy DPF. While the official narrative demonises diesel, some drivers show that proper maintenance can achieve near-nonexistent emissions.
Premium diesel vs. cheap diesel: myth or reality?
Real-world experiences divide opinion. On one side are those who claim all fuel comes from CLH and that additives are pure marketing. On the other, those who swear they notice clear differences: low-quality diesel causes higher opacity and a "tractor-like" engine sound. One striking case: after refuelling at a station where the owner saw someone pour a jerrycan into the diesel tank, the vehicle measured 0.06 opacity — the only time it failed to reach 0.00. After switching to another brand, it went back to zero. Coincidence, or does fuel really matter?
The role of the DPF and motorway driving
Diesel engines with a particulate filter (DPF) are far better at reducing opacity, especially when used on long motorway journeys. A driver with a 20-year-old Audi A3 with 308,000 km got 0.04 and 0.02 at recent ITV tests, while a Peugeot 205 without a DPF measured 0.4 (though the limit back then was 2.5). The key is that the DPF burns off particles through regeneration cycles, and short city trips prevent that process. That's why a car that does lots of motorway driving can keep its exhaust pipe practically clean, as the photos in the test reports show.
Additives: trick or necessity?
Some drivers turn to products like Endado smoke reducer or Repsol's Nexa renewable diesel to pass the ITV. Others, however, believe they're unnecessary if the car is in good condition and runs on the right fuel. The debate is on: while some argue additives are a temporary fix for dirty engines, others insist that with basic maintenance and quality diesel, the car passes without any help.
Is 0.00 really possible, or is it a measurement error?
One participant with technical training argues that no diesel can emit transparent smoke when accelerating; that a reading of 0.00 would indicate a faulty meter. However, those who have achieved it at multiple ITV tests reply that the device consistently gives them 0.00 to two decimal places, and that the third decimal is probably low but not displayed. The discussion remains open: how reliable are opacimeters, really? Or can a modern, well-maintained diesel actually emit fewer particles than a petrol car?
While politicians ban diesel, some drivers show that a 15-year-old car can be cleaner than many modern ones. The question nobody answers is: if these vehicles pass with 0.00, what's the point of environmental badge restrictions?
Related forum debates
A diesel BMW with 205,000 km on the clock has passed every ITV roadworthiness test with 0.00 opacity, except once when it ran on adulterated fuel. The recipe: premium diesel, motorway driving and a healthy DPF. While the official narrative demonises diesel, some drivers show that proper maintenance can achieve near-nonexistent emissions.
Premium diesel vs. cheap diesel: myth or reality?
Real-world experiences divide opinion. On one side are those who claim all fuel comes from CLH and that additives are pure marketing. On the other, those who swear they notice clear differences: low-quality diesel causes higher opacity and a "tractor-like" engine sound. One striking case: after refuelling at a station where the owner saw someone pour a jerrycan into the diesel tank, the vehicle measured 0.06 opacity — the only time it failed to reach 0.00. After switching to another brand, it went back to zero. Coincidence, or does fuel really matter?
The role of the DPF and motorway driving
Diesel engines with a particulate filter (DPF) are far better at reducing opacity, especially when used on long motorway journeys. A driver with a 20-year-old Audi A3 with 308,000 km got 0.04 and 0.02 at recent ITV tests, while a Peugeot 205 without a DPF measured 0.4 (though the limit back then was 2.5). The key is that the DPF burns off particles through regeneration cycles, and short city trips prevent that process. That's why a car that does lots of motorway driving can keep its exhaust pipe practically clean, as the photos in the test reports show.
Additives: trick or necessity?
Some drivers turn to products like Endado smoke reducer or Repsol's Nexa renewable diesel to pass the ITV. Others, however, believe they're unnecessary if the car is in good condition and runs on the right fuel. The debate is on: while some argue additives are a temporary fix for dirty engines, others insist that with basic maintenance and quality diesel, the car passes without any help.
Is 0.00 really possible, or is it a measurement error?
One participant with technical training argues that no diesel can emit transparent smoke when accelerating; that a reading of 0.00 would indicate a faulty meter. However, those who have achieved it at multiple ITV tests reply that the device consistently gives them 0.00 to two decimal places, and that the third decimal is probably low but not displayed. The discussion remains open: how reliable are opacimeters, really? Or can a modern, well-maintained diesel actually emit fewer particles than a petrol car?
While politicians ban diesel, some drivers show that a 15-year-old car can be cleaner than many modern ones. The question nobody answers is: if these vehicles pass with 0.00, what's the point of environmental badge restrictions?
Related forum debates
Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (46 replies).
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