One of the more common questions to come up when someone begins shopping for a Spec Miata is: “Which is the best year car for Spec Miata?”
To sum it up in a couple sentences: Buy the first NA or NB that you like, with a good cage, that is in your budget. The current parity between the cars (Minimum weight differences, restrictor plates, etc) is actually quite healthy and there is minimal advantage/disadvantage between the cars. A car that has a slight edge on one track, may be at a disadvantage on a different track. Unless you are running at the absolute peak of the national championship field, nearly all of the perceived difference between the generations can be chocked up to driver skill, car prep, and the quality of the build itself (engine).
The only exception to “they all work fine” is for heavier people and NA 1.6’s (1990-1993): In order to make weight you need to be a Horse Jockey, generally ~180 lbs or less. Even at 180 you’ll be finishing each race on fumes to get close to the minimum weight.
Miatas eligible for Spec Racing per Generation:
NA: 1990-1997 (Popup Headlights)
The first generation of the Mx-5 Miata, the one that made everyone fall in love with the car. There were about twice as many NA Miatas sold as NB’s, so there are a lot of cars and cheap body parts around, despite the age of the platform.
1990-1993 “NA6” NA first gen with 1.6 engine.
Min weight 2275: No restrictor Plate
Known as the “cheaper” Spec Miata, but not necessarily because it’s a bad option. Most old and cheaper builds are the earlier 1.6 cars (As NB’s were still quite new and expensive when the class began), so the older builds help drive the reputation and costs for the platform. It gets an unfair reputation as the “Bad” or “Slowest” Miata, but they can be quite formidable, especially on tight tracks where the lighter weight can really shine.
Minimum weight is the biggest hurdle for buying a NA 1.6. With the lowest minimum weight in Spec Miata, a heavier driver will not be able to even get close – and won’t be able to take advantage of the car’s biggest strength. The weight of the average American Male and Female is 198 and 170lbs, respectively. The Average Male driver won’t be able to get within about 30 lbs of the minimum in most NA6 Miatas, the average female will barely squeak by. Want a cool shirt system? Even more. Passenger seat, more yet, etc.
However, If you’re shopping for a starter car on a tight budget, I wouldn’t say no to a good deal on a 1.6, even if you’d end up overweight. You will be at a disadvantage, but an extra 30-40 lbs probably won’t be the biggest thing holding back a rookie driver.
Advantages: Lowest minimum weight, Generally advantageous on short tight courses (Like Lime Rock Park). Typically cheaper.
Disadvantages: Hard to get very close to minimum weight with a heavy driver. Simple and Temperamental Airflow meter makes a car more affected by weather changes. Lots of old builds out there with questionable cages and missing updates.
1994-1997 “NA8” NA first gen with 1.8 engine
Min weight 2400: No restrictor Plate
The Black Sheep of the Spec Miata world, for some reason. I’ve heard multiple people say these cars have the most potential in a top build… Yet I see extraordinarily few in the top championship ranks of Spec Miata. The good part is they are generally one of the cheaper cars you’ll find for sale, and with a 2400lb min weight, you have less trouble making minimum weight with heavier drivers.
I’m biased here, as I happily race a NA8. I think the NA8 cars are generally the best valued Spec Miata. They are plenty capable of holding their own in competition, but the lack of regular cars in the upper echelons of the class certainly make it look like both NA’s (NA8 especially) could use just a bit more help in the balance department.
Advantages: Usually the cheapest generation of Spec Miata, relatively low complexity. No Restrictor Plate. Acceptable platform for heavier drivers.
Disadvantages: NA suspension and aerodynamics, but the same weight as the NB1. Perform okay everywhere, but don’t stand out anywhere either.
NB: 1999-2005 (Fixed Headlights)
The NB Miata has taken over as the dominant Spec Miata chassis. While their advantage over the NA may be minimal, it is enough that nearly anyone starting a fresh build is (understandably) choosing them. The NB chassis has a slightly wider track width and improved bump steer. They also have a slight aerodynamic advantage over the NA cars. Whether the NB1 or NB2 is the flavor of the week really depends who you ask, where you are racing, and what color shirt you’re wearing.
Because NB’s are “where the money is”, expect to see more decked out, expensive builds. Rotisserie builds are more common than you might expect for what is (was?) a “budget” racing class. They are nearly always more expensive than the NA cars: Partially for the minute performance advantage, but mostly because of the greater detail that has gone into building cars recently.
While the NB cars are newer, they are prone to terminal rust in the front frame rails (Right at the sway bar attachment point). Be sure to check for this before purchasing or starting a new build.
1999-2000 “NB1” NB second gen with 1.8 engine.
Min weight 2400: 38mm Restrictor Plate
The ‘99 cars have a 1.8l engine like the previous NA generation, but with a bit more compression ratio and a better flowing cylinder head. The NB1 retains the same minimum weight as the NA8, though it requires a 38mm restrictor plate.
Advantages: Despite the smallest restrictor in the class, a top built 99 has potential to make the most horsepower of all years. That plus the aerodynamic advantage means they bias towards being the best option for long tracks like Road America, Watkins Glen, etc.
Disadvantages: The NB1 is a two year model, and junkyard/core motors are becoming increasingly tough (and expensive) to find. The NB’s are typically more expensive than NA cars.
2001-2005 “NB2” NB second gen with 1.8 VVT engine.
Min weight 2425: 40mm Restrictor Plate
The big change for the NB2 is the addition of Variable Valve timing. While not a knockout horsepower adder, it does have more torque through the rpm range. The restrictor plate is slightly larger than the 99-00, but the NB2 has another 25lbs of minimum weight.
Advantages: The extra grunt from the VVT helps NB2’s dig out of slower corners, so it’s a popular choice for moderately tight tracks. The grunt may also help “bail you out” if you mess up a corner. The heaviest minimum weight makes it the most generous platform for larger drivers who still want to be close to the minimum.
Disadvantages: NB2’s are the most complicated of Spec Miatas, so there could be more to diagnose (VVT system, immobilizer, etc) in the [rare] event of an issue. The NB’s are typically more expensive than NA cars.
Between the NA and NB generations, there really is no “Wrong” car to buy for a Spec Miata. As I said earlier, buy the nicest car you can find with your budget. While some cars may have a small advantage at a specific track, a different generation will often take the edge at another venue. Across a season of racing, any miniscule advantage is averaged as you travel to different tracks.
As we speak of the differences between years, keep in mind: Any advantage is within squeezing the last 1% of performance out of the car, so if you’re new to the class or racing you will not be anywhere near the level where it matters. Just find a car and come racing!
To run Spec Miata, 6spd equipped NB cars need to be swapped to 5spd transmissions (and final drive swapped from the 6spd’s 3.9 to 4.3 of the 5spds). The later “sport brake” models also need their brakes to be downgraded to the standard 1.8 brakes.
Mazdaspeed Miatas (Turbo model offered 04-05) are not Spec Miata legal.
You may see many cars in the wild with different weights listed than their Minimum than you saw above. Cylinders are often overbored during the engine rebuild process, and the overbore requires a 15lb addition to the cars Minimum weight. (so 2290, 2415, and 2440).
NC and ND Miatas are not Spec Miata Legal. The NC has the newly formed “Spec MX-5” class, which hasn’t really seemed to take off. Whether the cars don’t have the same magic, they’re too expensive, or the timing was bad (Covid)… Either way, don’t expect Spec MX-5 to take over as the biggest road racing class in the country.
ND cars run in Global MX5-cup, but as a semi pro series (Running at 7 weekend schedule scattered around the country) it is not for the faint of budget.
The NC and ND cars can also run in many “catch-all” or power-to-weight based classes in clubs, but don’t expect the magic (or numbers) of spec racing.