We can think of Iron Condors as a combination of a short Strangle and a long Strangle further OTM. Buying the further OTM Strangle reduces the credit received and lowers the Buying Power requirement. Additionally, the long options create trade friction which dampens the Greek values of Theta and Vega.
In this piece, Tony, Frank and Michael G. explore the relationship between the credit as a percent of the underlying price and Implied Volatility for various strategies including Strangles and varying width Iron Condors. Because of their long options, Iron Condors have less sensitivity to changes in Implied Volatility than Strangles and experience less of a credit increase than narrow Iron Condors when the VIX pops.