The Citroen, which goes on sale in the UK next summer, is just 30mm longer, 36mm wider and identical in height to the Vauxhall.
In fact, the C3 Picasso is smaller than the original Xsara Picasso, yet it manages to cram in a similar amount of interior space.
With the rear seats in the C3 slid forward, there are 500 litres of boot space - the same as in the Xsara Picasso, which Citroen says it will continue to sell.
As is the vogue with MPVs these days, the C3 Picasso is packed with clever storage solutions. Those sliding rear seats are split two thirds to one third, and have adjustable seatbacks and a ski hatch for long, narrow loads.
If you need to shift something a little wider and longer (2.48m long, to be precise), the rear seats fold down simply at the touch of a button, the boot floor can be raised to the higher of two levels, and the front passenger seat can fold flat.
Citroen has even solved the perennial problem of somewhere to store the luggage cover if you need to fold down the rear seats - there's room for it under the twin-level boot floor.
Engine line up The C3 Picasso sits on the same platform as the Peugeot 207, although Citroen is quick to point out that it will be less sporty and more comfort-orientated.
Engines also come from the 207 - 90bhp and 110bhp 1.6 diesels, as well as 95bhp and 115bhp petrol engines which are shared with the latest Minis.
The models on display in Paris are fitted with new Stop-Start technology and six-speed automatic gearboxes, helping drop emissions to 110g/km.
The new Stop-Start system is said by Citroen to reduce emissions and fuel consumption by around 15% over current levels.
Expect prices to be competitive against the likes of the Vauxhall Meriva and Renault's Grand Modus, meaning a starting price in the region of £10,500.