The Z4 isn’t cheap to buy, but you pay about the same as you would for an equivalent Audi TT Roadster or Mercedes-Benz SLK, and less than you would for a comparable Porsche Boxster. Surprisingly big showroom discounts are available and these help to offset resale values that are very good but not as strong as a Boxster or SLK’s.
Official fuel economy and CO2 emissions are identical for all four-cylinder Z4s, if not a match for four-cylinder Audi TT Roadster models.
There's a big hike in price for six-cylinder 35i and 35is models, which are nowhere near as efficient.
Inclusive packages that cover all services for five years or 50,000 miles are very reasonably priced. You can pay more for a package that also covers maintenance costs for the same period.