Not driven an IQ but I've driven 2 Aygo and if it's worse than the Aygo then don't go near it and the Aygo is supposed to be the next "class" up.
How many mpg do you consider to be economical anyway?
Conversely I think the aygo/c1/107 are cracking little cars, cheap (from Peugeot or Citroen) basic and honest. The iq is more expensive and tries to tap into the mini market. Cleverly packaged but you pay what is imo too much of a premium for it, if you like them you like them though cant do any harm taking it for a drive
Billy bargain when you compare it to the Aston Martin Cygnet
I actually drove back from football behind one a couple weeks ago, couldn't believe people around here actually bought the things.
Different cars for different markets though - similar size but different concepts. If the OP wants the IQ i can't see the Aygo trio being an alternative