I use a cup holder & have done for years. I have wired them to air vents, hung them on doors & all sorts. As long as the antenna is above the dash, they work fine. The only draw back I have found is that the longer & slightly better 38cm antennas are too tall, so it's a smaller antenna that needed.
Also prefrably buy a deeper cup holder, as like that the radio sits more securely in it.