The number of tests for 2012-2019 doesn’t represent the number of cars on the road in that segment. Anybody know the actual % of cars on Calif roads in each of the three segments?
70% of excess emissions identified by roadside testing? I wonder what they mean by “roadside testing”? 30+ years in Calif, I’ve never had any of my vehicles emissions tested by the side of the road.
They use portable sensors that can ‘read’ the pollutants put out by your car as it drives by. Really! Saw a report on this, it would actually cost less to have mobile test units travel around and identify the gross polluters, then give them a ‘fix it ticket’. They showed that the majority of pollutants is associated with the small fraction of gross polluters. This study here shows that it’s the older cars most responsible.
I wonder if one segment is much more responsible than the others? No doubt the pre-electronic fuel injected segment is worse than the post-. And the vehicles with carbs and no cat , likely the very worst.
Yes, pre-2000 cars produce 70% of the total car pollution.
I’m wondering about the total amount from each of the sub-segments, at least the two major sub-segments, OBD I - 2000, vs pre-OBD I. With all the data available to these folks publishing the charts, you’d think they’d just publish the total pollution from each model year along with the % of cars in each model year compared to all cars on the road in Calif. Then we could slice & dice it anyway we wanted. The info they publish vs not publish, in the way they present it, sort of makes me think there’s a hidden agenda involved.
I’m sure that data is being collected however that wasn’t the focus of this document.
They investigated the percentage of vehicles that passed station testing but failed roadside testing. Some of failures are due to the age of the vehicle and others due to false testing by corrupt stations.
For model year 1976-1999 vehicles that are subject to tailpipe testing as part of their Smog Check, Table 2 summarizes the results from BAR’s Roadside Inspection Program. As may be expected due to the greater age of the tailpipe tested fleet, overall weighted roadside failure rates for model year 1976-1999 vehicles tended to be slightly higher (19% vs 18%) than for model year 2000-2006 OIS tested vehicles.
As required by statute, BAR’s analyses of roadside data for this and prior SCPRs have attempted to identify and quantify the causes of excessive failures at roadside inspection. Two of the most important factors are vehicle age and the performance of the Smog Check station and inspector that certified each vehicle prior to roadside testing. Older model year vehicles tend to fail more at roadside than newer model years, and vehicles that were certified by high-performing Smog Check stations (those with an FPR score of 0.9 or greater) fail at a significantly lower rate than vehicles that were certified by low-performing stations (e.g., those with an FPR score less than 0.1).
These California BAR tests included OBD and tailpipe tests on a chassis dynamometer. Participation was voluntary and did not affect the vehicles biennial emission test status.
I wonder how they differentiate a “pass” b/c of good tailpipe testing station numbers vs an automatic “pass” b/c the owner spent the required minimum amount on repairs to address a problem, obtained the valid registration sticker, but it still didn’t pass the tailpipe numbers.
That is not a “pass”, that would be a ““failure”” with a waiver.
Pay attention to the small details and you will pass the emissions inspector’s licensing test on the first attempt.
My friend living in other part of Calif still hasn’t been able to get their car’s OBD II readiness monitor to complete. Registration has now expired.
Poor planning on your friend’s part does not constitute an emergency on the shop’s part 
Tell them to stop filling the tank all the way up, keep it between 1/4 and 3/4 tank for a while and then have the monitors checked… Pretty sure this was discussed in another thread… lol
It has been more than two weeks, can’t they get someone to drive the vehicle for 20 minutes?
With a temporary operating permit, the vehicle can be driven for 60 days after the expiration date.
The notice to renew registration and smog the vehicle arrives well in advance, roughly 2 months ahead of the registration expiration date
People would be smart to bring the vehicle to start planning the trip to the smog inspection place as soon as the notice arrives, not wait until the last minute
That way, if the monitors aren’t ready, or the vehicle needs repairs to pass, you should theoretically have enough time to get that taken care of before the registration expiration date
They went to the smog testing station within a week of receiving the notice. Upon initial test, no evidence that the car didn’t meet emission standards. The only problem was one of the readiness monitors hadn’t complete. Smog shop techs told owner just needed to drive the vehicle more, then come back. Came back twice, still a no-go. Smog shop continued to say “just drive more!”. So they drove from San Diego to Las Vegas & back. . On the plus side, they had a good visit to Las Vegas. Downside, car Emitted a lot of pollution out the tailpipe on the long trip . Back to the test shop, readiness monitor still incomplete. So they were forced to pay $300 to a mechanic, he connected the shop’s pro scan tool, and was able to complete the readiness monitor in a 15 minute drive. Before the Las Vegas trip the registration had expired, but they just drove the car anyway. Car owner very PO’d. The only accomplishment for all this, besides moving the $300 from the car owner to the mechanic, was for the state’s politicos to make another Calif emissions-testing opponent.
One of my jobs working in high tech Silicon Valley was to review technical reports, looking for indications the author was blowing smoke, hiding data, misleading conclusions, hidden agendas, etc. IMHO that report shows a lot of indications for reasons to be suspicious. These are the sorts of things I’d look for
The conclusion you form by reviewing the report may be accurate, but imo this study smells like 3 day old fish, & much more published data is required. For example,
For each model year, from 1976 to 2023
In summary, if the conclusion is valid, the raw data should clearly support it. So let’s see the data!
I read and write technical reports, and don’t share your misgivings.
Fair enough. If so, the published data above will prove you correct. All I’m saying is, let’s see the data!
I think the writer’s goal was to condense a huge amount of data down to a chart and text that clearly presented the main conclusions. I think they succeeded.
That was only an excuse to take a vacation, the emission monitor tests would have timed-out before they reached Victorville.
Why the excessive pollution, was the vehicle in need of repair?
That is the penalty for being a bad driver and proof that it is an easy task.
Two weeks ago, I repaired a vehicle with a turbocharger wastegate fault. After repair, I erased the fault and road tested while watching the emission monitors. The scan tool doesn’t accelerate the monitor tests, it only indicates when it is time to return to the shop. Pictures below: incomplete/complete were taken 8 minutes apart. Evaporative emission system monitor is incomplete and takes overnight but is not necessary for the state test in California or Nevada.
