A quick look on the mamas and papas website shows that the pilkos infant carrier is an evolution of the model we used.
we didnt have the base that it fits to with ours, if we had i expect it would have been easier to fit in the car.
we used it from birth until about 9 months, when she was new born we used the inserts to make it more suitable for a small child.
the little touches are what made it for us like the front and rear pockets on the carrier meaning we could do away with the need for a seperate changing back, as we could store nappies wipes bottles etc in the pockets.
as for fitting in to the car they may be getting confused with the isofix system for child seats which requires isofix fixing points in the car.
our infant carrier fitted in every car we put it in. in some cars when fitting it in to the rearseat you needed to push the front seat forward to fit it in properly.
for example when we fitted it in to a renault clio/megane, peugeot 309 and 306 estate and a vauxhall astra estate the front seat needed to be moved forward, but in the ford mondeo there was plenty of rrom even with the front seat fully back.