Is the Nissan 350Z a good investment?

The thesis

The late 313hp HR 350Z with GT Pack (Rays wheels, Brembos) represents the final, best-developed iteration before the 370Z. Clean examples remain affordable at £11-18k, well below your budget floor, but collector-grade low-mileage cars are 'few and far between' as most were thrashed. As one of the last big-engine, naturally aspirated, manual Japanese coupes, appreciation has begun—early GT4s and Anniversary models lead. Risk: pricing is below your stated minimum, suggesting you want a more premium asset.