Negative consequences of owning two cars simultaneously? (UK)?

I'm wondering with a large amount of disposable income, what the the disadvantages of owning two cars at the same time.
The two cars I was looking at was a Ford Fiesta ST and a BMW 330D.
They are both second hand vehicles with 40-60k miles on them (as I really dislike depreciation on vehicles when bought new).
I understand you'll have to insure two vehicles and pay tax etc.
Both cars would cost roughly £25,000 combined to buy.

The fact that you could buy a new and better single car for the same money tops the list…