As many agree, the CX60 lacks insulation and soundproofing quite severely. In my opinion, the road noise is bad, tyre roar is bad and the overall pleasant ambience in the cabin is ruined by this, for what is hailed as a 'premium' car, for me it wasn't acceptable, but it's easily and cheaply fixed.
There are many ways to add soundproofing, and a variation of materials. Some use deadening, then add absorbing materials, some use heavy mass such as thick rubber sheets. I wanted something that can add a level of refinement, without being obvious or requiring any modifications to carpets, panels, clips etc.
Please add your own soundproofing methods on your CX60 to this thread - please include some photos!
I used in my 'Stage 1'
2.5mm Killmat in the doors (90% coverage) and bonnet
2mm + 2.5mm Killmat in the boot and rear wheel wells/arches
Overall I used an entire box, which cost around £65. and added around 7kg of mass/weight.
![Image]()
The difference it has made is remarkable, the car is near silent now, the only noise coming from the front wheels and engine. So my next project will be the front wheel wells and transmission tunnel / bulkhead - PHEV owners may not need to do the bulkhead as the 4 pot isn't as noisy as the 6 cylinder.
I didn't photograph it very well so the photos do show it before it was finished - they are merely there to give you an 'idea'
No photos of the doors but the poor Mazda TSB 'insulation' was stripped off and the Killmat applied covering around 90% - the doors are Bentley weight now! The Mazda TSB was merely to reduce the flex and tinny sound in the doors, which it did do to an extent, but its effectiveness in sound insulation came down to how the dealer technician applied it, how much material was used and what grade. The job varies heavily. Mazda have now began putting two tiny 1mm sheets in the doors to reduce the flex from the factory, but it does little for actual sound proofing.
In the doors you see a marked improvement of road noise, I cannot hear passing cars or traffic now when inside.
It looks something like this
![Image]()
The boot floor was the next area. It's a little ugly for a few reasons ;
(this is on a Diesel, the PHEV boot floor seems to be somewhat different, so your application may vary)
1.You have to work around the areas where the storage bin sits - if i covered those areas it would raise the floor a few mm depending on the thickness of material you use which could look odd and cause the floor to rock and vibrate, and I'm too OCD for that. The way i did it I get 90% of effect without anything looking odd or causing any nuances.
2, Mazda has used some of that cheap and fairly useless spray sound deadener on this car (my PHEV had nothing like this just bare metal) so i had to go over that where i could as I wasn't into stripping it all off. You can literally ‘tap’ around the boot and hear a horrible metal tin can sound. With the Killmat added it's a solid ‘thud’ sound. Much better.
I forgot to take a photo of it finished as there was quite a bit more added after these photos where taken.
![Image]()
The biggest thing i noticed was inside the rear wheel arches - there is ZERO sound insulation in the arch/rear quarter. A tiny bit of thin foam to stop the carpeted cover rubbing on the paint and that's it. The arches sound like a tin can when tapped. With a rear wheel bias car like the CX60 it was no wonder the tyre roar was so bad. I tried to get as much Killmat in there as possible but was hard without stripping it all down to pieces. If i did it again I could probably manage more or if i engaged the help of someone with tiny hands!
![Image]()
Next up was the bonnet.
There are support welds on the second skin, so you cannot put whole sheets in there, its basically cut out pieces and put them in as best you can.
![Image]()
![Image]()
This massively reduced the sound of the engine outside, and inside the cabin, getting rid of any higher pitched noises making it sound a lot deeper and refined. However one thing to note, it does reduce the glorious sound of the inline6 so be warned!
One thing to note is that by putting this insulation in, you do 'unbalance' the 'noise' in the car, so now, the majority of noise comes from the front wheel wells, so you must do this eventually to balance the 'noise'.
The Stereo sounds so much better now as well and subwoofer thumps nicely and you don't have to turn it up on motorway to drown out the tyre roar.
Overall there is such a larger sense if 'peace' in the cabin, its less fatiguing on long trips and much closer to the likes of a Q5 and X5 in terms of refinement.
The best bit is that its all invisible too when the panels are put back into place. Best £65 I’ve spent on improving this car I think!
Next jobs (will update thread as I go along)
1. Front Wheel Arches - I've been contemplating which way to do this, to either add material to the arch liner like this (concerned if the clips will still be long enough to refit)
![Image]()
or to the wheel well like below. This is the 'better' job but I was concerned about water getting in to the butyl and causing it to fall off or moisture being stuck potentially causing issues further down the line. I think I will do it the latter, but use butyl roof flashing tape to 'seal' the edges.
![Image]()
2. Bulkhead and Transmission tunnel -
This is probably not needed on the PHEV unless the EV whine annoys you, but the 6cyclinder does have a 'throbbing' engine note that can get a bit tiresome in traffic and long trips, and its transmission banging on startup is just embarrassing.
It will mean the seats and centre console out, and maybe even parts of the dash. Its a big job, and I am not sure how successful it will be, so this will be the 'final' step if I decide to go that far.
Another option is to add sound 'absorbing material' to all the crevices behind the dash - this is easy to do, you just have to be careful not to block any vents and make sure the material you have used is fireproof.
As I have the sun roof, there isnt a lot of roof to soundproof, so I will add in a few sheets of butyle at the back and then a couple of panes of this stuff. Those without a sunroof would be advised to do the whole roof, its a tin can.
![Image]()
3. Tailgate - will drop the read panel and add some Kilmat where I can
Other aids in the question for 'silence'
All Season tyres with noise cancellation, such as Pirelli Scorpion All Season PCNS, which were designed for Jaguar Land Rover. Other brands have their own noise cancellation systems but the tyre size is quite rare
![Image]()
Remember - Prep is key to success!
Ensure the surfaces are cleaned with iso or prepaint immensely, so the material can stick. Take time rollering the material until it is completely flat. The Killmat stuff is really good as it has raised surfaces on the silver part so you can see where you have rollered. Its hard work and if you do it on a hot day you'll be sweating like a convict on the railroad, but you don't want any moisture or air to be behind the material.
There are many ways to add soundproofing, and a variation of materials. Some use deadening, then add absorbing materials, some use heavy mass such as thick rubber sheets. I wanted something that can add a level of refinement, without being obvious or requiring any modifications to carpets, panels, clips etc.
Please add your own soundproofing methods on your CX60 to this thread - please include some photos!
I used in my 'Stage 1'
2.5mm Killmat in the doors (90% coverage) and bonnet
2mm + 2.5mm Killmat in the boot and rear wheel wells/arches
Overall I used an entire box, which cost around £65. and added around 7kg of mass/weight.
The difference it has made is remarkable, the car is near silent now, the only noise coming from the front wheels and engine. So my next project will be the front wheel wells and transmission tunnel / bulkhead - PHEV owners may not need to do the bulkhead as the 4 pot isn't as noisy as the 6 cylinder.
I didn't photograph it very well so the photos do show it before it was finished - they are merely there to give you an 'idea'
No photos of the doors but the poor Mazda TSB 'insulation' was stripped off and the Killmat applied covering around 90% - the doors are Bentley weight now! The Mazda TSB was merely to reduce the flex and tinny sound in the doors, which it did do to an extent, but its effectiveness in sound insulation came down to how the dealer technician applied it, how much material was used and what grade. The job varies heavily. Mazda have now began putting two tiny 1mm sheets in the doors to reduce the flex from the factory, but it does little for actual sound proofing.
In the doors you see a marked improvement of road noise, I cannot hear passing cars or traffic now when inside.
It looks something like this
The boot floor was the next area. It's a little ugly for a few reasons ;
(this is on a Diesel, the PHEV boot floor seems to be somewhat different, so your application may vary)
1.You have to work around the areas where the storage bin sits - if i covered those areas it would raise the floor a few mm depending on the thickness of material you use which could look odd and cause the floor to rock and vibrate, and I'm too OCD for that. The way i did it I get 90% of effect without anything looking odd or causing any nuances.
2, Mazda has used some of that cheap and fairly useless spray sound deadener on this car (my PHEV had nothing like this just bare metal) so i had to go over that where i could as I wasn't into stripping it all off. You can literally ‘tap’ around the boot and hear a horrible metal tin can sound. With the Killmat added it's a solid ‘thud’ sound. Much better.
I forgot to take a photo of it finished as there was quite a bit more added after these photos where taken.
The biggest thing i noticed was inside the rear wheel arches - there is ZERO sound insulation in the arch/rear quarter. A tiny bit of thin foam to stop the carpeted cover rubbing on the paint and that's it. The arches sound like a tin can when tapped. With a rear wheel bias car like the CX60 it was no wonder the tyre roar was so bad. I tried to get as much Killmat in there as possible but was hard without stripping it all down to pieces. If i did it again I could probably manage more or if i engaged the help of someone with tiny hands!
Next up was the bonnet.
There are support welds on the second skin, so you cannot put whole sheets in there, its basically cut out pieces and put them in as best you can.
This massively reduced the sound of the engine outside, and inside the cabin, getting rid of any higher pitched noises making it sound a lot deeper and refined. However one thing to note, it does reduce the glorious sound of the inline6 so be warned!
One thing to note is that by putting this insulation in, you do 'unbalance' the 'noise' in the car, so now, the majority of noise comes from the front wheel wells, so you must do this eventually to balance the 'noise'.
The Stereo sounds so much better now as well and subwoofer thumps nicely and you don't have to turn it up on motorway to drown out the tyre roar.
Overall there is such a larger sense if 'peace' in the cabin, its less fatiguing on long trips and much closer to the likes of a Q5 and X5 in terms of refinement.
The best bit is that its all invisible too when the panels are put back into place. Best £65 I’ve spent on improving this car I think!
Next jobs (will update thread as I go along)
1. Front Wheel Arches - I've been contemplating which way to do this, to either add material to the arch liner like this (concerned if the clips will still be long enough to refit)
or to the wheel well like below. This is the 'better' job but I was concerned about water getting in to the butyl and causing it to fall off or moisture being stuck potentially causing issues further down the line. I think I will do it the latter, but use butyl roof flashing tape to 'seal' the edges.
2. Bulkhead and Transmission tunnel -
This is probably not needed on the PHEV unless the EV whine annoys you, but the 6cyclinder does have a 'throbbing' engine note that can get a bit tiresome in traffic and long trips, and its transmission banging on startup is just embarrassing.
It will mean the seats and centre console out, and maybe even parts of the dash. Its a big job, and I am not sure how successful it will be, so this will be the 'final' step if I decide to go that far.
Another option is to add sound 'absorbing material' to all the crevices behind the dash - this is easy to do, you just have to be careful not to block any vents and make sure the material you have used is fireproof.
As I have the sun roof, there isnt a lot of roof to soundproof, so I will add in a few sheets of butyle at the back and then a couple of panes of this stuff. Those without a sunroof would be advised to do the whole roof, its a tin can.
3. Tailgate - will drop the read panel and add some Kilmat where I can
Other aids in the question for 'silence'
All Season tyres with noise cancellation, such as Pirelli Scorpion All Season PCNS, which were designed for Jaguar Land Rover. Other brands have their own noise cancellation systems but the tyre size is quite rare
Remember - Prep is key to success!
Ensure the surfaces are cleaned with iso or prepaint immensely, so the material can stick. Take time rollering the material until it is completely flat. The Killmat stuff is really good as it has raised surfaces on the silver part so you can see where you have rollered. Its hard work and if you do it on a hot day you'll be sweating like a convict on the railroad, but you don't want any moisture or air to be behind the material.
People have been using butyl for engine bay soundproofing for decades.
