My V5C and the space where decibels should be is blank, which interested me so whilst sitting in the garden enjoying a G&T this afternoon and waiting for the Cottage Pie to cook and F1 to start I've had a look and found this.
According to the UK Government Vehicle Certification Agency
The external noise emitted by passenger cars has been controlled since 1929 when the Motor Cars (Excessive Noise) regulations were introduced. New cars are now required to meet Europe-wide noise limits. These have been progressively reduced from 82 decibels (dB (A)) in 1978 to the current limit of 74 dB (A) established in 2016.
The level of noise for new models of cars is recorded at their type approval test. Note that off-road vehicles are allowed to be 1dB (A) louder and wheelchair accessible vehicles or armoured vehicles are allowed to be 2 dB (A) louder.
The noise levels quoted above are the maximum levels that are permitted for new vehicle types. Many vehicles produce lower levels of noise, and it is illegal to modify the exhaust system of a vehicle to make it noisier than the level recorded for that model at type approval.
A new EU regulation was introduced from July 2016, Regulation (EU) No 540/2014, phases in tighter noise limits over 10 years, together with a revised, more representative test procedure. By 2026 the limit for most new passenger cars will be 68 dB(A).
OK, so what did my 400 Sport achieve decibels wise at type approval? (As it is missing from the V5C). Well a quick query to the UK VCA returns "Noise Level dB(A) Moving" = "70".
JAGUAR F-TYPE 400 Sport, 18MY 3.0L V6 (400PS) Supercharged Coupé & Convertible Auto AWD, A8-AWD
Naturally had a look at some other cars as a guideline. All Db(A) figures. As recorded from cars type approval system. Drive by Noise in DB(A)
Current UK Limit for New Cars = 74
Jaguar F-Type 2.0L P300 = 70
Jaguar F-Type 3.0L 400S = 70
Jaguar F-Type 5.0L 550R = 71
So I think we all know and agree that a v8 is louder than 2L etc. But this of course is drive by noise. A set test where a car drives past a sensor at 20 metres away at a certain speed. I had a look at some other cars such as Mini Cooper S which was 71 and Vauxhall Astra 1.4 which was 72!
Imagine this question in a pub quiz. Your sat 20 metres away and bog standard Astra drives past and then a v8 F-type. Which would be noisier? The government data used for type approval says it would be the Astra!
So why is this relevant to the original post?
It is illegal to modify the exhaust system of a vehicle to make it noisier than the level recorded for that model at type approval under the 1929 Motor Cars (Excessive Noise) regulations.
So lets say that some time in the future you get caught by a naughty noise camera. All you would have to do is plead not guilty by post, attach a copy of the Government Type Approval for your vehicle and send it back. The burden of proof would be for court to prove their case of which if they tested your car and presuming your exhaust is standard it should return the same number on the Type Approval and then you suggest that perhaps the camera was faulty or another noise interfered. Ultimately, unless you have attached a drain pipe as an exhaust to 1L Corsa you'll be fine.
In fact it sounds (excuse the pun) such a bad idea I would bet it is scrapped after the trial. A waste of tax payers money. What we really need is some of those old fashioned things you used to see...... the ones who used to stop bad drivers, the uninsured, the middle lane hoggers, etc. Traffic cars and police I think they used to be called.
** note, all figures recorded are for active exhaust off.