This is an edited version of a document from the Australian forum, scream and shout if you want, it can be modified to Uk tastes[;)]
First Generation – NA Mk1
NA6 89-late 93 Mk1
The original, the most raucous. Equipped with a 1.6l DOHC Inline 4 producing 85kW around 114 bhp, pushing a one tonne roadster, and a throwback to the simple days of motoring.
Pros
Simplicity - Maintenance is always the simplest on the NA6.
The Exhaust note - a highly subjective issue, but most people agree the exhaust note was the sweetest in the stable.
Cons
Rarity - Need to put in the hard yards to find one in good condition nowadays, but it isn’t impossible, they are 16 years old at the least and most spend their lives being driven after all.
Creature Comforts - Not comfortable (by todays standards) and definitely not a car for those who want to be pampered
LWSC - Some owners have reported Short Nose Crank failure (especially on imported Eunos models) which is fully detailed on the parent forum, but in effect, every early model (ie pre July 1991) NA6 has a potential to need an Engine change or a new crankshaft if LWSC strikes. In some cases, repairs may be effected to the crankshaft, but the longevity is variable, depending on the extent of the damage, and the quality of the repair. LWSC is an unofficial term, coined by enthusiasts, and not by Mazda.
Suits: Traditionalists and the old fashioned, people who appreciated the days of the old British sports car but also the reliability, Also a very good starting point for the DIY warrior but perhaps not a fair representation of what motoring is like today engineering wise
NA8 93 – 97 Mk1 1.8
Perhaps a more grown up NA6
Pros
An Enhanced NA6 - Bigger brakes, Bigger engine, Stiffer Chassis among the regular evolutionary enhancements
Power - The MX5 now has the BP ZE 1.8l engine with 98kW 128-135 bhp depending upon the year (post July 1995, a higher compression engine was fitted, generating more power).
The NA8 also comes with strengthened differential, axles and driveshaft
Creature Comforts - Power steering become less widespread for the MX5 at this point in the generation; prior to the introduction, virtually all UK MX5s and imported Roadsters had power steering. Post-introduction, the UK Mazda importers decided to make PAS effectively an option, by introducing the S-trim level. For Roadsters, PAS continued to be virtually standard, except for some extremely rare factory clubman editions.
Cons
Rarity - Not as extreme as the NA6, but similar case, they are old, and they are driven
Comfort - Still not a car to choose if you’re used to the modern day comfortable car
Suits: Very good as a tuning base be it at street or club racer level, those who want the purity of the original NA6 but with a little more ability
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Second Generation – NB Mk2
NB8A 98 - 00
A more modern evolution of the MX5 mantra, younger, stronger, more comfortable, but nothing the lesser for it
Pros
Safety - Introduced Airbags as standard
Performance - Enhanced BP engine now puts out 106kW 140 bhp (thereabouts)
Comfort - Much less harsh than the original NA, more sound deadened, comfier. With the introduction of the NB8A also came the introduction of the glass rear window soft top, some say it was a blessing to the rest of the MX5 stable as roof lowering is fully able to be a one arm, stop light affair. A 6-speed gearbox was available on some UK models, and many Roadsters.
Cons
The MX5 is starting to grow up, driving experience is starting to soften up (it just won’t feel as fast as an NA to some)
Suits: Those who are worried about the NA ownership experience (mainly concerns to do with age) but still like the visceral nature of MX5 motoring
NB8B 00 - 03 Mk2.5
Another evolutionary step for the MX5, small tweaks leading to big differences
Pros
Engine power has been bumped up to 113kW 155 bhp thanks to the addition of valve timing control
Addition of 6th speed in gearbox gives the power transmission a greater range of flexibility
ABS is now standard as well and also similarly to the NA6 compared to NA8 argument, has bigger brakes (Sport model only), better seats, brighter lights, the addition of foglamps and additional chassis strengthening over the NB8A
Along with the additional chassis strengthening, a front suspension strut tower brace is added, it is equipped with a better stereo system and more useable cup holders
Also '02 year cars and later, are OBDII (on board diagnostic) compatible
Some have argued that this was the best of the breed in terms of the mass produced MX5s, Best Motoring claims that the NB8B represents the MX5 that Mazda Japan was always aiming for and finally had produced in terms of driving experience and dynamics
Cons
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Suits: For the more discerning taste, for those who have grown out of the juvenile character of the NA<o:p></o:p>
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Third Generation – NC Mk3
NC no model change to date 05 - present
A complete revamp of the MX5 mechanicals, but with as much as possible adherence to original philosophy
Pros
Newest, still perfectly possible to be under factory warranty
Much more comfortable than previous iterations of MX5, suspension and damper settings
Now with a 2.0 MZR putting out 118kW 160 bhp. Note European NCs have significantly different gearing from the ROW.
Even more capable than previous generations of MX5 with subtle suspension tweaks as it has the most recently honed dynamics
Easiest MX5 to live with with auto being widespread and the option of powered plastic roof
Also '07 models onwards come with Traction control and Dynamic Stability control as standard, making emergency management of the MX5 just that… much more manageable
Cons
Questionable suspension settings from factory, some were just not adjusted right, many motoring publications state that suspension behaves in a very unsettled manner, but easily sorted with a good wheel alignment
Driving experience much more muted compared to previous generations of MX5, definitely not as raw
Suits: Those who are looking for the newest possible representation of the MX5 mantra, much more diluted over the years, but no less able.
Note: this has been obviously written by a NB-FL owner, who’s discerning taste is questionable.