Emissions: ULEZ - has anyone modified a Mk1 to meet ULEZ?

I’ve had my Mk1 Mx5 for 22 years and would be heart broken to have to sell it. But I live in Highbury N London and the ULEZ comes in next year.
Having kept on top of maintenance, had bushes done, suspension - lots of worn bits replaced, got though plenty of brake calipers, many soft tops (crims love to tear them…) replaced steering rack, had plenty of re-sprays… I have a car that’s in really sound condition.
Surely the brain that governs the mixture / fuel injection could be modified?
Any suggestions? Guy

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Are you sure your car won’t be exempt from ULEZ regs because of it’s age?

I bet there are loads of tuning type people waiting in the wings of this very forum ready to offer tuning and component mods to make it comply if you’re not exempt. How’s the queen going to get on with all the old motors she’s got stashed at Buck House? There must be a solution of some kind that doesn’t involve parting with loads of cash?



The problem is that the acceptance of a vehicle for the ULEZ is based upon the manufacturer’s homologation data and therefore its registered emission standard compliance. This defines the vehicle’s Euro emission standard and also the allowable emissions for it to pass an MOT. With enough money spent (catalyst etc, or maybe a later engine) it MAY be possible to bring an old vehicle up to later, or current, standards. However, getting such a vehicle approved individually and essentially ‘reregistered’ with DVLA as meeting a later, or current, emission standard (so the ULEZ cameras recognise it as ‘acceptable’) is likely to be the stumbling block. However, I know it can apply ‘in reverse’ for kit cars where an older engine is fitted in a newly built vehicle and therefore meets an ‘older’ emissions standard for MOT. Maybe some sort of Individual Vehicle Approval may be a route?

I’ve had experience with this from the two wheeled side of the fence. I had a wonderful, beautiful italian motorcycle. I loved that bike with all of my heart but could not afford the £200 extra every four weeks it would cost me to ride it into that London. So with a heavy heart I sold the beast, which was only a year too old for the ULEZ zone, and bought a replacement from a Japanese manufacturer. A few weeks after the ULEZ kicked in I found out that it was possible to have your bike tested by a motorbike place in Old Ford. If it passed it was a one off fee [£200 ish] and it was ULEZ free for the rest of my ownership. I had my old 1995 bike tested and it absolutely flew through the test, I’m sure my other bike would have too.

The reason my bike was not considered ULEZ exempt without the test is that manufacturers did not supply the [or probably even know] about the pollutants emitted at time of manufacture so without figures it was considered liable for the charge. If you have an older car it’s likely that the exemption will not be applied simply because the figures are not available. You might find that when the zone enlarges that there will be companies that pop up that can test the older cars, just like what happened with the bikes.

The Ulez test [for bikes anyway] is primarily concerned with the amount of Nox produced. Strangely older less efficient vehicles often produce less Nox than the newer lean burning ones.


Now that’s interesting. I had no idea that it was possible to get an older vehicle (well, a bike at least) tested and individually exempted for the ULEZ.

This is preying on my mind too because I commute in my Mk.1 to just inside what will be the expanded perimeter of the ULEZ. If I could get an individual exemption, even if that meant fitting a different cat or new ECU and tuning it to meet whatever spec is required, I’d absolutely do that.

The exemption for older vehicles only applies to cars over 40 years old. TFL say to prove your car meets the ULEZ standards you need to show them “A letter from the vehicle manufacturer’s homologation department stating the vehicle’s Euro standard or a conformity certificate”. Clearly Mazda is not going to issue a letter saying my old Roadster was built to meet Euro 4 NOx emissions because it wasn’t. But what is “a conformity certificate”?

Basically I think it’s what I was issued for my bike. It was put on a rolling road and measurements taken at various speeds and throttle openings. Hopefully something like that will be available for cars, my fear is that they won’t allow it simply because they want to get rid of older cars. Bikes are slightly different because their emission standards are lower in the first place and they are seen as a greener alternative just because they don’t sit idle for long.

This ULEZ thing is the reason I bought my 5. I had a small diesel car that did 65mpg for going up and down the M11 into work when the bike was moaning about the weather. Suddenly the car that qualified for a green car discount when I bought it is now a polluting menace! So I bought a sports car instead that does 33mpg but is allowed into the zone

I wonder what a typical NOx figure would be for a Mk.1 or Mk.2 MX-5. It would be a pity to argue for the right to pay to have an individual car tested for conformity only to find it can’t meet the requirement.

NOx is not measured for a MK.1’s MOT so I have no sense of whether it would be easy or hard for a Mk.1 (with clean injectors, a good cat and a healthy O2 sensor) to meet Euro 4 emissions. Might be a bit easier for a UK 1.8 as they have EGR which I gather is good for reducing NOx (Roadsters don’t have it fitted) but I guess it depends on what the nature of the test is.

Not something I’d do personally to mine, but there was a post (I think on the Miata forums since it was in America) about someone who converted their MX-5 to electric, presumably that would pass the ULEZ.
Think it also cost something like £20k :face_with_raised_eyebrow:

Nox is not something they test on any mot afaik.

People are getting confused here as BrilliantBlackBirday suggests between what is tested on an MOT and the much more complicated tests that is done for Euro approval purposes.

The MOT test did not check emissions until 1991

The Mk1 covers prior to Euro 1, and Euro2

It would be uneconomic to have the cars tested, it takes days to do the type approval type tests and would cost many thousand pounds to do them.

I’m aware that the Euro 4 emissions test is a lot more involved than any MOT emissions measurement, and measure g/km rather than a proportion of the total exhaust gases, but I don’t think it’s completely out of the question to do it. I’m sure I read an article by a journalist who got his old petrol Golf and new diesel car rigged up and tested to compare the two. Yes it was expensive and took, if I remember correctly, a whole day for each car, but I’m interested to know exactly what would be involved and what might help improve an individual car’s emissions rather than just assume it’s impracticable.

Mk.1s continued to be made and sold after Euro 2 came into force and Mk.2s, which are not fundamentally different, coped similarly with Euro 3.

I wonder whether if a group of us Mk 1 owners got together we could share the cost, if it meant that all of our vehicles would benefit? For that we’d need a number of people willing to put a modest sum into a pot… Would the MX5 Owners club be willing to look after any funds we collected and help to ensure fair play?
I’ve also started a conversation on the letters page of Classic and Sports Car - the editor says it is going to be published.
all the best Guy

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Guy, can you give us a “heads up” about which edition of Classic & Sports Car this is likely to be in?



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Just to let you all know, that the current issue of Classic and Sports Car has the letter in. There’s an E type Jag vs the 1st generation Corvette on the cover.
All the best Guy

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Hi everyone, just providing a friendly bump to this thread to see if anyone has any update on being able to get their vehicle certified for ULEZ? Currently living in the forthcoming expanded ULEZ zone and as October draws closer I’m looking into all options to keep my car as opposed to moving, finding somewhere to keep my MX5 outside of the zone or worst case having to sell my car.
Cheers, Oliver.

I keep musing about going electric, but it’s not affordable yet. (There’s a business opportunity…) So annoying eh?

Same, either that or the Rocketeer V6 conversion but again out of my budget unfortunately! Off to the MX5 Restorer at the weekend, will see if they have any bright ideas…

If anyone has any sensible ideas, do mention them.
My sweet car was resurrected out of garage of mould and flat battery (always disconnected of course) to have a run round the block, last week. These moments are precious. But it feels like the clock is ticking. 30 yrs old in Aug.

Yesterday our beloved MK-1 euros passed her MOT. Brilliant car - love it to bits. I asked the garage if they knew of any ways around the ULEZ or ways of converting it but apparently there aren’t any. They were as depressed as me on the subject :frowning:

There must be a way!! I don’t want to get rid of a perfectly fine car in October. This is not good for the environment either by creating more waste.

Anyone here got any updates? I got my vintage motorbike fully compliant a couple of years ago - had to do a test and then got a certificate but for less than £200 I can go around London without having to pay those charges every day.

I’d be happy to spend more for getting the mx5 in the TFL ‘good list’ :slight_smile:

Take care x

‘Vintage’? Surely every vehicle ‘taxed’ as ‘Historic’ (over 40 years old) is exempt anyway?