Small travel system recommendation pls

[sanfair]

I mostly use a sling for my 7wo DS and prefer to use it 99% of the time as I tend to go most places by public transport.

I am looking for a very compact travel system. Basically, I just need a car seat with wheels to use on the rare occasion we either rent a car or go out to visit my SIL by train and get collected by her from the station.
Ultimately, I am looking for something that is very small and maneuverable.

Any recommendations?

[thisisyesterday]

quinny zapp?