You don't get a 4.9L V8 engine though which is the main appeal of the Z8, but It does look quite convincing in the photos and I'd like to see one in the flesh. At between £5k & £6k ballpark to do the conversion, not includng the donor car (and labour if you don't do it yourself) it's not cheap and you'd really have to want the Z8 looks to consider it. In the end you'd still have a Z4 but in different clothes, and personally I really like the Bangle designed Z4 - which is why I bought mine, so I'd see no point in doing this.