"automated" washes can mean a lot of things. You have everything from swirly-whirly brush washes to touchless washes. Neither is ideal honestly, but if you MUST use some kind of tunnel wash make sure its a touchless. The ones with brushes and big strips of cloth wiggling from the rafters are just going to obliterate your car.
A touchless isn't ideal for 2 reasons (but still better than a brush wash)
1) In order for it to 'clean' without some kind of mechanical agitation it has to rely on heavily acidic or alkaline cleaners to do the work. This means that any coating you may have on your car (wax or sealant) designed to protect the finish from the elements is being degraded and stripped away. This becomes an issue b/c the next time salt hits it you're going to potentially see damage. Theres also the negative impact on trim drying out from repeated exposure to the harsh detergents.
2) The false sense of clean. No touchless wash is going to clean the car 100%. Don't believe me? Go thru a touchless wash then wipe any section of the car with a white towel. I promise you there will still be a layer of film/dirt on the finish. It'll definitely be cleaner than when you started, but its not completely clean. This becomes an issue if you intend to wipe down, dry, cover, or even possibly wax your car after the fact. You'll be grinding those particles into the finish causing damage.
In winter, if you drive your car you have to resign yourself to the fact there is going to be some kind of compromise -
- You live with a dirty car and let the elements do what they will.
- You tunnel wash it and just decide to correct the paint later.
- You wash it yourself in the cold and freeze your butt off.
When the weather is really sloppy here I just do a complete blast off at the local pay n' spray 1 or 2 times a week to keep the buildup from getting too bad. If you're lucky the place will have heated water (don't use the brush) and you can blow all the crud out from the underside and knock 90% of the grime off of the exterior in just a couple of minutes. No sense in REALLY getting it clean if its going to be driven and get sloppy again.
When there is an extended break in the weather I do a full and proper 2 bucket wash, dry, and reapply my sealant and dressings to protect the exterior thru the next cold/wet/snowy spell.