I need to buy a new car as had an accident in mine 😞 what cars do all you doggy people have??? I need: room to fit 2x medium crates in back, must have good mpg, and decent on tax and insurance. My car was a Citroen berlingo multispace. £4kmax!!!!!!help and ideas please!!!! 

try a fiat doblo  same thing as a berlingo only normally big fuel consumption and mileage are probably the same insurance the same maybe mine is low 300s with two drivers on it

must have good mpg

Whatever car you get, I suggest you look at getting an LPG conversion, but, make sure who ever does the conversion has come highly recommended for their work or the conversion can go badly wrong >>>due to poor fitting<<<, stay well away from London based conversion companies, check out your local LPG prices.
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If you don't need more than 3 seats maybe consider a van? I drive a Citroen dispatch now and it's been brill on fuel and perfect for 4 dogs daily. Insurance has been surprisingly good too.

I agree with corgilover, have a look at the Doblo, I have one and there's masses of space.