Wrong MOT Brake Efficiency Calculation for Mk2 Scirocco
Posted: Sun Nov 07, 2021 2:15 am
Just a quick heads up that I have reason to believe DVSA have uploaded the wrong test weight figure for at least some versions of the Mk2 Scirocco onto the MOT system, which massively suppresses the brake efficiency calculation. This apparently only applies to test centres that use a manual roller brake tester, as more modern automated roller brake testers calculate the brake efficiency using the actual weight of the car at the time of the test, not the theoretical test weight figure recorded by DVSA.
The last two years my GT II has only just scraped through, which I found surprising, as this had never been an issue on previous tests. After a lot of probing with the MOT garage and then DVSA, DVSA confirmed that they had used a brake test weight of 1230 kg. This didn't sound right to me as the maximum permissible gross weight of the car on the VIN plate is only 60 kg more at 1290 kg.
Up to very recently, DVSA didn't supply brake test weight figures so MOT testers were expected to enter their own figure from a published source, such as an MOT data wall chart. I managed to get hold of an out of print Autodata MOT brake test data chart published in 2010 for vehicles on the road before the year 2000 on ebay. This shows a test weight figure for the Mk2 Scirocco of 1040 kg, much closer to what I would expect for the weight of the car plus fuel plus driver. The figure for the Mk1 Scirocco is even lighter at 970 kg. The figure for the Passat/Santana GL5 is listed 1230 kg, so I wonder if the admin assistant's (or quite likely IT contractor's) eye slipped down a few lines as they were manually entering the data from the wall chart onto the MOT database.
This makes a massive difference to the brake efficiency calculation. Using the Autodata figure, the brake efficiency on my Scirocco would increase from the stated 51% (pass mark 50%) up to 61%. I think this is a good figure for a non-ABS car with rear brake pressure limiters, even comfortably over the 58% pass mark for cars registered from 2010.
DVSA customer service suggested I email them and ask the MOT policy team to review this discrepancy. I will update the thread when I hear back, hopefully within a few weeks.
The last two years my GT II has only just scraped through, which I found surprising, as this had never been an issue on previous tests. After a lot of probing with the MOT garage and then DVSA, DVSA confirmed that they had used a brake test weight of 1230 kg. This didn't sound right to me as the maximum permissible gross weight of the car on the VIN plate is only 60 kg more at 1290 kg.
Up to very recently, DVSA didn't supply brake test weight figures so MOT testers were expected to enter their own figure from a published source, such as an MOT data wall chart. I managed to get hold of an out of print Autodata MOT brake test data chart published in 2010 for vehicles on the road before the year 2000 on ebay. This shows a test weight figure for the Mk2 Scirocco of 1040 kg, much closer to what I would expect for the weight of the car plus fuel plus driver. The figure for the Mk1 Scirocco is even lighter at 970 kg. The figure for the Passat/Santana GL5 is listed 1230 kg, so I wonder if the admin assistant's (or quite likely IT contractor's) eye slipped down a few lines as they were manually entering the data from the wall chart onto the MOT database.
This makes a massive difference to the brake efficiency calculation. Using the Autodata figure, the brake efficiency on my Scirocco would increase from the stated 51% (pass mark 50%) up to 61%. I think this is a good figure for a non-ABS car with rear brake pressure limiters, even comfortably over the 58% pass mark for cars registered from 2010.
DVSA customer service suggested I email them and ask the MOT policy team to review this discrepancy. I will update the thread when I hear back, hopefully within a few weeks.