I know my story may seem boringly obvious but I have tried all these so called economy offers and each time left with a bad taste, hidden costs and hassle. I travel a lot and in the end I went back to Hertz. Actually I never feel ripped off because even their costs are quite effective these days and sometimes I have been surprised with an upgrade. Beware of selling options such as full insurance no excess, whcih indeed may cover you fully technically but read the small print carefully, there will be hidden monsters. Especially look to the extra in insurance, it may be worth paying extra for the peace of mind especially if driving in "difficult" driving areas.
It's a bit like low cost airline you gets what you pays for. There will be hidden costs for what you expect to be standard, late flight pickup, variable quality of supplier, etc. As I said I went back to the majors at least I see what I am paying for. I also take out the extra insurance options when in countries or parts of countries where bump accidents are commonplace, even if I don't end up using it I have found that life is too short to suffer the hassle of being totally fleeced if I have even a small scratch.