The gas price is somewhat misleading. With diesel engines, figures of >40mpg are not uncommon, even with SUVs, whereas in the US something like a Ford Explorer will often achieve around half that. Effectively the comparative cost of fuel can be halved or more by an efficient engine.

As for the other comments about size, if you need to move five adults in comfort a bigger car is a necessity. While small cars may still be the norm, larger vehicles are hardly uncommon in the UK.

Regardless, a second driver fee of $200 US for the fifteen days is not minuscule compared to either the cost of the rental or the cost of fuel.