Ironically, the only researched sentencing that is used as a statistically significant deterrent is the
Capital Punishment or the Death Penalty...
Viewing some of the stats, they may be weak, like a P < 0.04999, but it is still significant on a 2 tailed, heterodecastic analysis.
Giving lashes to anyone is "Cruel and Unusual Punishment" and could be labeled a torture by some circles. What is it going to teach the offender if you want to not have recidivism?
The other issue is why did these men feel they needed to sexually assault and rape a female friend? I do not know how Saudi courts operate, and we may not care about that issue, but I do not think they are "crazed lunatics" unable to control themselves to savagely brutalize a woman, today. I think this was a planned activity because they knew how this poor girl behaved and when she refused, they overpowered her... Simple as that.
Should they be punished? Definitely. Should the girl be punished? Like I said, was a rape kit put on her? If not, they authorities do not have any right to put her on trial because it becomes her words against the offenders. If they did, and she violated the law of not riding in the car with male non-relatives, at minimum, she should be made to pay in community service or administrative work.
Regardless of what we think of their laws, Saudi Arabia is a sovereign nation. However, I think it a human rights violation to punish any female who has had to endure a sex crime. That is my opinion. I could be wrong.