2006 BMW
Z4 M Roadster

3.2L S54 inline-6, naturally aspirated — the same engine as the E46 M3. North American spec: 330 hp / 262 lb-ft; European spec: 343 hp. Six-speed manual only, no auto option. 0–60 mph in 4.6–4.9 s, electronically limited to 155 mph. M-specific suspension, CSL-spec front brake rotors, limited-slip differential, quicker steering rack, quad exhaust tips, and a curb weight of ~3,230 lbs — notably lighter and more raw than modern equivalents.

Genuinely rare versus regular Z4s. Worldwide production: 5,070 Roadsters. North America: ~3,042 units (≈60% of production). The Z4 M Coupe is even rarer at ~4,275 worldwide / ~1,815 NA. Certain colors are extremely limited — Interlagos Blue Metallic (~478 Roadsters), Sepang Bronze Metallic (~100, very few with matching interior). Imola Red, Black Sapphire, and Titanium Silver are more common but still desirable.

Currently in the 'affordable enthusiast' phase. Average market: $25,000–$35,000 for decent examples (50–80k mi). Clean, sub-40k-mile or rare-color cars reach $45,000–$60,000+. High-mileage or project cars sit in the low-$20k or teens range. Depreciation has largely finished; the best examples are stabilizing or climbing.

Tailwinds: short production run, the rising S54 (alongside the E46 M3), raw analog driving experience, and the M badge. The Coupe has appreciated faster than the Roadster — mirroring the Z3 M dynamic. Most enthusiasts expect strong Z4 M Roadsters to appreciate meaningfully over 5–10 years as they earn modern-classic status, especially as new sports cars get heavier and more electronic. Convertibles appreciate slower than coupes due to top/seal wear and broader market appeal; rod-bearing and bushing maintenance tempers some collector interest.

Prioritize service history over mileage. Insist on a pre-purchase inspection focused on the S54 (rod bearings, VANOS, cooling system). Rare colors — Interlagos Blue, Monaco Blue, Sepang Bronze — and low miles are most likely to hold and appreciate. Still undervalued versus its driving experience and rarity.