My car was pretty good acoustic wise, but I wanted to improve it regardless. Still going to do a bit more when I find the time, but it is really not absolutely necessary. I have added about 1.8m2 of butyl, you don't need it everywhere. So far about 5.4m2 of acoustic foam & have about another 1.8m2 ready to add. A few layers of engine bay acoustic insulation plus a bit of fire wall aluminium insulation & stuffed left overs around the battery for a heat shield. It is about a weeks worth or work to do the car. Didn't do the floor as the insulation is so thick I didn't think it was worthwhile. Up till today still don't.

Over the new year I drove to Kosciuszko NP. The roads south of Sydney are concrete & they create a very irritating sound. Two months later back on the same road but further this time, the car is a lot quieter. There is no getting away from the sound but it has been reduced reasonably. It is the high frequency sound that has been cut back the most.

I bought a 1.3m2 piece of mass loaded vinyl without foam backing & used the front floor mats as templates but ran the vinyl a bit higher pass the steering column & also into the bottom of the fuse box.

I bought another sheet of the expensive bonnet lining & added another layer down about 350mm on the fire wall. Also stuck some on the inside of the fuse box but left a gap so one can still read the fuse locations. Plus stuck a few bits here & there. When I get time I will figure out where to add more.

Ceiling: for those without skylights! It is worth adding a layer of foam to the ceiling. Also shove in some polybatt insulation, it has cut back heat entering the car from above. If you have a dark coloured car it would be even more worthwhile.

I have stuck a bit of foam around the light console on the ceiling but not on the ceiling in the area above where the sun visors fold home. I will have another look at this area to see if I can get anything in that area. I think it is worth the effort if there is room, firstly to reduce heat as this area is a lot warmer than the ceiling behind. Also the car needs acoustic insulation in the front wherever you can put it to balance the car's sound. If the rear is too quiet the front will sound louder.

Still have to do the B column & door sills. Also bought a sheet of 6mm foam so I can stick it where the thick acoustic foam will not fit.

Back from a month in Tasmania. The car drove really nicely on Tasmania's pretty ordinary roads. Also a lot of them are very narrow, windy & bumpy, but the car drove nicely! I couldn't be happier that I have added acoustic insulation. It simply makes the quality of driving so much nicer. Still going to add a bit more but it is really impressive so far, even more so on the concrete roads south of NSW with the car's all terrain tyres.

At the end of the day a weeks works for an even quieter car!

I'm giving you 10 points for effort , well done !
Anything to make the cabin more comfortable to be in is worth it l reckon :)

A few more photos of the acoustic insulation. I pulled the car apart a second time & a third in some places & installed insulation wherever I could. All up about 2 weeks on the car. Get panel removing tools & a roller, makes life easier & you do a better job.

Ceiling front. I didn't use butyl on the roof, only foam. Maybe on a van over the driver & passenger it could be worth doing.

Ceiling front. Have since stuck acoustic foam on the backside of the ceiling lining. Also stuck foam in the metal holes where the sun visors sit. Have noticed this has cut down heat coming into the car. Polybatts in the ceiling made a bit thinner to fit, probably about R 0.8, but it's a worthwhile effort.

Ceiling rear.

Ceiling rear.

Ceiling centre to rear & inside structural beam. (Double up backing film long enough to push foam in then pull off tail of backing film. Save film from large pieces to reuse in these situations)

Stuck foam on the back of every single trim panel. Also stuck butyl on A, B, C & D columns.

This quietened down the mirror motors, nice improvement, feels nice & solid now!

Window frame trim.

Window frame trim, around entire window frame.

Door, I stuck more on the trim panel as it was easier. There is more foam than in this photo.

Added more & removed some high spots!

Top edge of door trim panel.

Boot panel, used to get some condensation here, more so on the tailgate. (Blue hose is for my triple ARB compressors setup)

Side of footwell.

Butyl on the front footwells, didn't do much on my car as the floor already had very good insulation.

The multi layered block on the inner side of the firewall made a big difference.

Insulation between the two firewalls in the car.

3mm, 6mm, 10mm & 12mm acoustic foam. The 12mm silver foam is for vans, it's more solid, should have got it sooner for the car to fill more bulky spaces.

Acoustic insulation in door pockets & lined with boat carpet.

Stuck 3mm & 6mm on the garage door out of interest. Cuts outside street noise down a reasonable amount.

We traveled last winter in the south west corner & up to Kalgoorlie & through the centre of Australia. We clearly noticed that the car was a lot warmer at night than the previous year, we mostly sleep in the car. No more condensation on the panels. Much slower to heat up during the day. 

We also have cut windscreen sun shades to size to fit every window & use 2 shades cut to size for the windscreen also exactly to size.

It was bitterly cold near Orange, -2°C outside the car in the morning but quite reasonable inside. Ice on the bonnet. Two sunscreens inside the windscreen.

I did try to get as much foam up around ear level in the car, not easy. Have done this in a computer room many years ago & it does deaden sound. At the end of the day you still have sound in the car but it is a reasonable amount less & has a much nicer tone. Feals more luxurious. I recommend putting in the effort & in the scheme of things it's not that expensive except for the high grade engine bay fabric. Do inside the car first but install it front, centre & rear or you will get the sound balance of the car itself out of balance which feels strange, ie if you only do the boot the front will feel louder.

I have replaced all the trim panel clips with clips with rubber gasket trim clips if they didn't have a rubber gasket which help reduce noise transmission to the trim panel.

A few more photos.

Tailgate.

Tailgate trim panel & I stuck foam in the window trim panels as well.

Dashboard trim, there is a second layer of foam on top of this as there was enough room.

More dashboard trim.

Front door frame.

Front door frame trim. (Trim clip in foreground has rubber gasket, the other one doesn't)

A column trim, was careful to split the acoustic foam across the trim panel as this is designed to split for an airbag.

Boat carpet from Whitworths Marine.

(3rd air compressor & 4 litre air tank - actually only 3.7 litres as I filled it with water to measure as I felt it was a touch too small. All unclips for draining)

I have also lined the back of the glovebox with foam. Also used some mass loaded vinyl on the front footwells under rubber floor mats & ran it up the firewall to some extent.

Boat carpet in centre console. (TPMS now on dashboard. Worth its weight in platinum!)

When we get a bit of road noise,we put a USB stick in with some great traveling music,turn up the volume and Eureka the road noise disappears.Cheap and you can sing along,the KISS principal.

I have 11 speakers around the car, sounds even better with acoustic insulation. The best bit is corrugated roads are more bearable!

Recently I was in the car doing some additions. While at it added a bit more insulation. I just try to put it anywhere I can. It's probably become more of an interest to prove a point just how much one can quieten a car. It works & the quality of driving is worthwhile.

It's not that expensive & if you have the time just get in there & do it. It will keep you occupied under the current Covid situation & while at it you can clean all the dust out from behind the trim panels.

If I buy another car it will be the first thing I will do before any other modifications.

I have partly removed the console between the front seats. Found a few spaces in there, but careful to leave enough clearance for the console sliding cover. So, some pyramid insulation on the small section of bare metal of the transmission tunnel, a block of foam under the forward & permanent cup holder & electronic handbrake, some insulation down either side & behind the gear stick mechanism.

Also a few small bits of pyramid insulation at the rear of the console under that tray at the tail end. I also removed the plastic trim (2 screws up through the top) around the driver's instrument panel.

There is a reasonably large gap above the actual display & under the dashboard, so pushed pyramid insulation in the gap.

While at it I ran a power supply from the fusebox to my ARB TPMS sitting in the bottom left corner of the instrument display.

Have also filled in the bottom of the A column trim panels with pyramid foam to the bottom of the airbag mounting.

Also more under the dashboard right up in the corner under bottom of the windscreen, passenger side. I have removed the rear footwell carpet mat holders ages ago, they were a pain in the neck when carrying water containers for camping.

There is a hole roughly 5cm to the bare metal floor, so stuffed a lot of offcuts of pyramid foam in through the pairs of small holes through the carpet.

After getting the car back together went for a drive to make sure everything works.

Well, that was an improvement in noise reduction, probably one of the biggest single steps in improvement to date. Those Cones of Silence are looking that bit closer, very happy!

I have added the 25mm foam (non mass loaded) to the front 1/3 section & the car seemed quieter, more so from outside. A lot of room in the ceiling.

Stuffed some foam through the holes, the area in the roof above the doors. 

Have now done the middle & rear sections. With the 10mm foam I originally put in the roof it is all acting like an acoustic bass trap, a tight bass which is nice. 

Will have to take it for a decent drive, but the first brief impressions are that the things are quieter from other cars passing.

I have been for a drive now with the additional 25mm plus the first lot of 10mm I originally put in the roof. I also stuck 10mm on the ceiling lining just over the driver & front passenger, second round of pulling the car apart. This was to try & balance the noise in the car, because I found if you get the rear too quiet, the car sounds wrong. 

Wow, that was impressive! 

The additional 25mm foam showed how much sound was coming into the car via the ceiling even though it never felt like the sound ever came from there. Probably there is some noise transmission through the largest panel of the car & also that the entire roof now has in total 35mm of foam & 45mm in the front (this is a touch thick now, but as I already installed the second layer of 10mm on the top side of the ceiling liner I wasn't going to pull it off). The polyester batts I have left in the roof. 

The car really feels like it has double glazing. Noise from other vehicles is impressively controlled, quiet & feels distant from the car. 

The only "offensive" noises now are really a bit of transmission noise. As I have the petrol engine it will be a bit quieter than the diesel, but the lower pitch of a diesel should be well controlled. 

The noisiest sound now is the all terrain tyres, even though the actual noise is in all respects is pretty quiet. I purposely drove over reflectors on the road & other road imperfections which all are very quiet & sort of removed from the car. So the underlying noise from the tyres is that AT drone they make, more so when they are older. 

In general on my last holiday I have noticed the the AT tyres seem to sound better on dirt roads than sealed roads. 

If you have road tyres I think the quality of the sound would be truely impressive. 

For those in Australia, Whitworth Marine have the 25mm foam, you will need 2 sheets for the ceiling. I have used the non mass loaded foam on the roof, but I had bought a sheet of mass load foam but did not use this in the ceiling. I got this for the engine bay & have cut a few pieces to test but removed them at this stage. Now with the roof done adding more in the engine bay I don't think it is worthwhile. 

For those with skylights if you can fill the roof around the edges without interfering with the roof mechanism I think it should improve sound quality a lot.

Conclusion: Butyl for stopping metal resonating, but you do not need to go overboard with this. Which is good as the butyl is heavy. Use as much foam as possible & as thick as you can fit in the space. Probably up to about 50mm if that is possible. Doors & behind boot trim panels, fill in as much as you can. 

Get spare trim panel clips as you will break them. Trim panel removal tools, not that you need them much, but they are really worthwhile when needed & a roller for the butyl.

Have you considered golf?

Lot of time and learning  and  the pay off is the satisfaction at the end when the results are as anticipated or sometimes even better ...well done.

Mike Harding wrote:

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Have you considered golf?

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 Not interested as I only get to enjoy a 500m drive!

KJB wrote:

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Lot of time and learning  and  the pay off is the satisfaction at the end when the results are as anticipated or sometimes even better ...well done.

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 Thanks for your observations.

It has been an interesting process & I was often pulling the car apart for something else anyway. I did a lot of hunting around the internet & couldn't find any really good quality information & really thorough jobs.

After one has pulled the trim panels off once, it is a piece of cake second time around. To get the ceiling down I have to pull off every panel starting with the boot sill trim, all columns, handles, sun visors. Install foam & all back together in 2.5 hours. So it's not that much of an effort.

We plan on keeping the car but on the remote possibility we do replace it, installing acoustic insulation will be the very first thing I do.

It is the same as sticking insulation in the house, which we have done extensively, you don't see any bling, but you get quality of life.

Did this about a month ago.

Being bored to tears thought I would experiment with some 50mm acoustic foam in the boot & a few more bits in the spare wheel well around & in the wheel rim.

The vertical piece on the back of the seat has the ridges cut off to jam behind the boot cover.

The foam makes a considerable difference to the rear of the car. Also doesn't seem to reduce sound from the subwoofer, but only did a quick test.

Also stuck some foam in the gaps under the vertical section of the rear seats. Will have to remove to fold seats down, which we rarely do. That makes a bit of a difference.

Other than filling the car entirely or doing double glazing I am now probably at an end. It has been an interesting & worthwhile experiment.