I was blown away by the new multimac carseat. It can transform a three seater car into a four seater one, suitable for kids of all ages, including babies backward facing, up to the age of 12. Three-seaters are also available for smaller cars, even sports cars and the Fiat. The seatbelts are all easily height adjustable. Most importantly, the carseat meets the rigorous safety regulations. You can even have it custom made to match the interior of your car. From £1200.  Multimac.co.uk