Just tried it in S1H, and it would appear I've been mistaken about this... With male or female in the car, the XFG weighs 1010kg. That means I've been motoring under a misaprehension throughout S1 in beleiving that those people who raced as women were doing so for reasons of mass.
In that case, seeing as Batterypark and myself (and I suspect many others) were wrong, why did so many male LFS drivers use female drivers? Is there another advantage I missed?