Mazda MX-5 2.0 Skyactiv-G ND

The ND's SkyActiv-MT six-speed gearbox was adapted from a transverse design for longitudinal use, and the 2.0-litre's higher torque has exposed weaknesses in synchro rings and shift forks. Mazda has issued at least five gearbox revisions since 2015, and early ND1 cars (2015-2018) are most affected. Symptoms include stiff or crunchy engagement into 2nd and 3rd gear, particularly when cold. A quick test during a purchase inspection: between 2,000 and 4,000 rpm, the shift from 2nd to 3rd should be possible with one finger — if it requires force, the gearbox likely has an early revision. Gearbox oil changes with high-quality GL-4 fluid (such as Redline MT-90) can improve shift feel but will not fix worn synchros. A synchro repair costs around €500-1,200 at a specialist, while a complete gearbox replacement runs €1,500-3,000 for the unit plus labour. The ND2 (2019+) received further gearbox improvements and warranty claims dropped significantly. Track use and aggressive shifting dramatically accelerate wear.

The rear hub carrier uses spherical bearings (rose joints) that are under-engineered for rough road surfaces. Some owners report failures as early as 25,000-30,000 km, though most cases appear between 50,000 and 100,000 km. Symptoms include a distinct knocking sound from the rear when driving over uneven surfaces. Mazda does not sell the bearings separately — the factory solution is replacing the entire rear hub assembly at approximately €400-500 per side including labour. However, aftermarket polyurethane bush kits from Polybush or Whiteline offer a durable and more affordable alternative at around €180-200 per axle for parts, plus approximately €100-150 for fitting. Mazda has covered a portion of hub replacement costs for some owners within or shortly beyond warranty, so it is worth requesting goodwill assistance from the dealer.

Mazda issued a technical service bulletin in 2018 regarding water ingress into the window regulator cables. Moisture enters the door cavity and corrodes the steel cables, eventually causing them to fray and break. Symptoms include slow or jerky window operation followed by complete failure. The entire regulator assembly must be replaced as a unit, costing approximately €100-150 for the part and €100-150 for labour. Both sides can be affected, though the driver's side usually fails first due to more frequent use. Preventive maintenance includes periodically greasing the cables and pulleys, and operating the windows regularly to redistribute lubricant. Later ND models (2018+) received a revised glass profile to reduce water reaching the mechanism.

The MX-5 ND has notoriously thin factory corrosion protection on the underbody, subframes, and suspension mounting points. Surface rust can appear within the first two to three years in salt-treated climates. Subframes have only a minimal flash of black paint that begins corroding almost immediately upon exposure. While this surface rust is primarily cosmetic initially, it can eventually affect structural integrity and complicates later suspension work (seized bolts, corroded mounting points). Professional underbody treatment with cavity wax and underbody sealant (such as Dinitrol products) costs approximately €300-500 and should be applied as soon as possible after purchase, with retreatment every five years. Neglected cars in wet or salted climates may need more extensive remedial work (€500-800) to treat advanced corrosion.

Early ND models (2015-2017) are most affected by an issue where the soft top's front edge rubs against the roll hoop plastic covers when folded down. Over time this can wear a visible mark or even a hole through the fabric. Mazda acknowledged the problem and offers a shim kit that repositions the roll hoop slightly forward to create more clearance. Some dealers have replaced affected roofs under warranty. However, even with the shims fitted, careful operation helps: lowering the roof from outside the car while guiding it away from the hoops reduces friction. A complete soft top replacement costs approximately €1,500-2,000 fitted (OEM), though the shim kit or careful use can prevent the issue entirely on many cars. RF (retractable fastback) models are not affected.

As a direct-injection engine, the 2.0 Skyactiv-G does not spray fuel over the intake valves, so carbon deposits from PCV blow-by gases can accumulate over time. The severity varies significantly between individual engines and driving patterns — regular spirited driving at higher rpm tends to keep valves cleaner, while predominantly gentle urban driving accelerates buildup. Symptoms appear gradually: slight roughness at idle, minor hesitation, and marginally reduced power. Mazda designed the Skyactiv-G with controlled valve temperatures to mitigate this, and many MX-5s reach high mileage without symptoms. If cleaning becomes necessary, walnut blasting is the standard remedy, costing approximately €300-500 at a specialist. This is typically only needed after 80,000-120,000 km, if at all.