Start with the only question that matters

A “640” badge means nothing if the car drives like a heavy nostalgia statue. So the spec sheet has one job: prove intent. Weight, geometry, and execution—then power.

1) Curb weight: the number that decides the whole story

If Nissan wants a modern hot-rod sedan that actually feels like a reborn 510, weight discipline can’t be optional. The target should read like this:

• Best-case: ~3,250–3,450 lb (light enough to feel alive)
• Acceptable ceiling: ~3,650 lb (still sharp if chassis is right)
• Red flag: 3,800+ lb (that’s a different car in a different class)

2) Powertrain: modern Nissan energy, production-real

Twin-turbo V6 intent (Skyline mindset)

If the 640 is positioned as a true performance leader, the powertrain needs “Skyline DNA” without being a fragile headline. Think a modern twin-turbo V6 approach, tuned for response and midrange punch, not dyno drama.

What “real” output looks like

• Street-real power: ~420–520 hp
• Torque that matters: ~400–480 lb-ft with fast spool and clean delivery
• Cooling priority: real intercooling, not marketing copy

3) Transmission + differential: the credibility test

A production car built to end the argument can’t be single-option theater. The real spec sheet would offer:

• 6MT that can actually hold torque
• Quick-shift auto that doesn’t dull the car’s identity
• LSD (non-negotiable) to keep power usable

4) Chassis + suspension: where Nissan race partners matter

If Nissan leans on race-proven partners for suspension development and geometry tuning, the 640 becomes a driver’s car—not a costume. The spec sheet should scream stiffness, control, and predictability:

• Modern multi-link rear + front geometry that rewards late braking
• Adaptive dampers tuned for real roads, not showroom softness
• Bracing and rigidity that make the car rotate cleanly

5) Brakes + tires: “hot-rod” means stop like one

Power is easy. Control is expensive. A credible 640 spec sheet looks like:

• Big brakes sized for repeat abuse (not one magazine stop)
• Performance tires from the factory (no “eco” compromise trim)
• Wheel design that reads modern Nissan—clean, production, popular style

6) Aero: functional, quiet, and correct

The 640’s look is the promise—boxy lines with rounded parts, modern surfacing, and a cleaner, more aerodynamic stance. If the aero is real, the spec sheet supports it with details that don’t feel like cosplay.

The verdict

If the 640 hits weight discipline, carries a modern Nissan twin-turbo V6 mindset, and backs it with real chassis + brake hardware, it becomes something rare: a production-real hot-rod sedan that respects the 510 without being trapped by it.

Next in the series

• Part 3: Lab Results — the testing facility verdict that decides if this is hype or history.