The internet is full of an advice and descriptions of mx5s ridden with rust. Is this peculiar to the mx5 or do all Mazdas suffer from it? For that matter do all Japanese manufacturers cars suffer rust?
My, albeit limited, experience says no. I’ve owned a 2003 Toyota Granvia with no rust issues and my partner has owned 2 Toyota and a Nissan, neither of which had any rust that we were aware of.
So what’s different about the MX5 that makes it more susceptible?
My simplistic take.
I have a Suzuki made in Hungary where they salt the roads. Reasonably well rust proofed. Toyota and Nissan have UK factories.
There’s no salting of roads in Japan.
My old Defender died of rust eventually. Cost me thousands in welding over the years. I could have put a new chassis on it but it needed a lot more work besides.
That wasn’t exactly close to the ground.
If you use any car in the UK in all weathers you risk it rusting to some extent eventually.
I have run New Mazda’s Honda’s Toyota’s and Suzuki’s for many years.
My wife has a 6 year old Suzuki Swift Sport which is used daily and its remarkably good underneath, my daughter just sold her 11 year old Suzuki Swift and it was also very good underneath.
I have to say its only MX5’s that have had rust issues mainly on the rear sub frames. Its such a shame they are not better protected.
I bought a 6 month old ex demo MX5 Miyako in 2010 and there was already traces of rust on the welds on the rear sub frame.
My ND is papered beyon comprehension. No salt (minus some dry salt in the first year). No rain. Under a half cover. No driving even when wet on the floor in the summer.
16.8K miles.
Underneath it’s no where near as good as my Mrs’ MINI, which has 2X the miles and is used ‘as a car’, i.e, in all weathers, year around. It looks frighteningly good underneath.
My well used NB had rusty sills which I had repaired; the chassis rails were ok. My 5 year old ND2 (which lives in a double skinned garage and is used on dry days only) had a little surface rust before it had rust prevention treatment by The MX5 Restorer. I have no major concerns about it rusting away during my ownership.
I have a 2 years old Suzy Sport. Your post does bring good cheer. I believe the Japanese Sport Hybrids, buit in Japan still…oddly…are actually multi dipped in various itchy etchy stuffs before base paints prior to finishings. I was told the shut lines and general quality of build is far better than their lesser cars in Asia somewhere. In the showroom, when I bought ours…I was hard pressed to see a difference…so I call BS on that one! But the OC bods confirm it…The chassis is 70 mm longer too! Go figure? Summat to do with housing the 48 volt hybrid battery nonsense.
Convertibles in general are more prone to rust. All convertibles include design elements that deliberately channel water through internal box sections. These box sections, by dint of the car being a convertible, are more complex than a tin top, creating additional moisture traps
Analysis of 2019 MOTs for % fails for “Body, chassis, structure” (ie, this is directional only)
Note, there will be survivor bias with older cars; when was the last time you saw a rotted Mk1 Fiesta or Cortina? When you look at some older cars, some have surprising low fail rates for this area, but that’s likely because all the rough ones have been killed off.
Data from the MOT files. The MX5 looks ok, except for those 2004 models, which when you dig into it, seems to be down to mostly chassis rot, ie the front chassis legs, which is the result of Mazda trying to extend the life of the NA substructure by improving front crash performance. I think Citroen took a similar approach, with the same effect.
As someone who has had a few Japanese imports I can assure you mx5s are not the only thing to come over that rusts. Anything buiit for the Japanese domestic market has minimal rust proofing and if it isn’t taken care of when the cars are brought over it won’t be long before everything underneath starts to scab up. I think the mx5 is just under protected from the factory, this plus that fact that it let’s in water to places you can’t immediately see without investigating, where it can do it’s work before you know it’s a problem.
I had a 55 plate (reg Jan 2006) Mazda 3 which I bought in March 2013, so 7 years old.
The underside was never treated and the car wasn’t particularly ‘loved’ …it was a work horse.
I traded it March '24 for a BMW.
The previous March, it had a small amount of welding done to both rear sills… the first welding ever in its lifetime… nothing much.
I thought then ‘this is the start of the demise’. It only had 70k miles on the clock. The body had a very small amount of rust on the front wings, wheel arches, and at least one/two dings on every single panel! It had lived a life!
The underside looked very crusty. Hence the trade in.
The car was now 18 years old… I got £500 pt ex… the first offer was £250!!
However, my 2010 Miyako… which I bought in 2016… had a little surface rust underneath . In 2021 I had her Dinotrolled… still looking good today.
But she’s never been on salted roads (…since 2016) and rarely driven in the wet.
She ‘lives’ on the drive under a full cover. I clean her regularly, after every trip out… and try to keep the underside, wheel arch lips, and the mud traps at the rear end of the sills in pristine condition. She’s looking good.
But if I hadn’t had the Dinatrol treatment and had treated her like the Mazda 3… I don’t think she would still be around today.
So yes, it maybe the MX5’s were built to be (very) disposable.
