Many years ago, I bought the MFJ 1664 screwdriver antenna, and since then this has been the basis of my mobile antenna system. It is comprised of a manually tuned screwdriver coil at the base, a small 4 and a half foot telescopic steel whip for using while driving, and a 10' telescopic aluminium whip (sold separately as model 1954) for using while parked.
The 10' whip is a little bit fragile, as many users have already testified on user reviews at www.eham.com and other sites. My first thought to improve on this was to purchase a solid steel whip, but since these aren't readily available in Spain, I had to wait a few years. It was by chance that one day my friend and customer Pablo Baulies was in New York and I asked him to pop into a nearby radio shack and pick on up for me. He obliged, although if he'd known the problems Air France were going to give him to bring it back, he'd have said no! The steel whip is great, but a bit heavy when its windy, putting a lot of stress on the base mount, and also is too big to be hidden away in the back of the car.
I continued to use mostly the 1954, having them break from time to time either at the base, or in between sections when they got corroded. These antennas do not like water! It's not a problem living in Valencia, but I would hesitate to use them in a wet country.
A couple of years ago my friend Rod EA7JX started stocking the new 12' version of this whip, the 1956, at his shop in Seville, www.hamradio.es , so I got one, this making it easier to install a full size 20m quarter wave using the whip, a 3' dx engineering mast, and the coil, with no turns added. However the first one suffered the same fate as the 10 whips and after about a year, failed between the second and third sections, rendering it useless.
The other day, local ham EA5FBD mentioned he had a 12' whip he wasn't using so we agreed that I would take it off his hands and give it some use. To my surprise, when we met, I saw that it wasn't the 1956, but a new model called the 1977, made of stainless steel. This looks to be a big improvement on the aluminium design. It's the same light weight, but the joints between sections are well defined and look to be much better (1956 left, 1977 right)
The base also looks to be a more solid design and also should be less prone to failure.
There's only one way to tell, so I have already pressed it into service and looking forward with interest to see how it fares with high winds, rain, and salt spray. I'll post an update in a few months time.
I see that MFJ also now make a 17' version, the 1979, which in principle should allow users to make their own quarter wave vertical for any band between 20 and 6 (and maybe even 2) metres. Good news for portable and semi portable operators like myself looking for a small lightweight antenna that will give full monoband performance with easy deployment.