I got one of their systems and have generally been pleased with it. The concept is simple - no dissolved solids in the water, so nothing left behind (i.e water spots) when the water evaporates.
I have tried the "wash, rinse and walk away" approach on a black car left in the sun, and would say that it works about 95%. Probably the pros and fanatics on this forum are never going to want to try that, but to an amateur like me, its nice knowing that I could give the car a quick rinse with the DI water and not worry (much) about residue. More likely, I am going to dry the car anyway, but I like knowing that whatever water I missed, or that which runs out from a crack when I drive away, is likely to leave little or no spotting.
Other tips: get hose quick-connects for the "in" and "out" sides of the system - makes set up and put away so much better.
The TDS (Total Dissolved Solids) Meter: This tells you how deionized the water coming out is, with 0 being the purest. With fresh resin cartridges, this will read zero for a while. The instructions say that anything under 30 will yield spot-free water. I tested this today with a black car in the sun with my TDS meter showing about 18-22 and I definitely got spots. Put in new cartridges, TDS meter read 0, re-washed car, rinsed, left in sun, and now 95% or more spot-free. Clearly, TDS 0 is better than TDS 20, so I'm not sure what the ideal cutoff should be.
So, these are some observations on a black car. With a white car (see avatar), I'm sure I'll be even happier.
Again, I like the system, but pros and fanatics are still going to dry right away, not wash in the sun, etc. (Where I live, not washing in the sun often means washing at night. That, and washing in the rain have amused my neighbors greatly, I'm sure).

 

I have found that I have to rinse particularly well to get every last drop of soap off or spotting occurs. Rear view mirrors and back glass are a couple of areas easily forgotten. So its basically 2 washes...one with soap and the other to get it all off. Does real well on my wheels...I like it and will continue to use it.

 

We have been selling the CRspotless units for 3 yrs now and have had very few minor issues. The unit works as advertised and all of our customers are experiencing what you are. Thanks for the observation!

 

I have seen the ads for the deionized water rinse systems in the rear 1/3 of Porsche mags for a long time. Seemed like a good idea especially for someone who has a Daily Driver where a 5% spot rate (as above) would be perfectly fine and time is a premium.

Not too thrilled about a several hundred dollar expense though. Saw the Mr Clean (no kidding... Mr Clean as in: bald guy in white tank top) spotless "system". Basically it is an $18 plastic spray gun with three settings: rinse for unfiltered water, soap to dispense their proprietary soap that supposedly has a water sheeting agent (no residue) and filter for a Pur brand filtered water spray after you are done.

My expectations going into the project was in line with the $18 price tag. However, I have to say that the filtered water worked just as advertised, no spots, even on glass. I was not overly in love with the soap they provided, nor the soap dispensing system through the gun, but no complaints with the filter system.

 

I've been using it for a year now and love it.

 

On behalf of the garage queens of RL.... ^ + 1 on the CR Spotless.

 

I have been using it for over two years and think it is great.

 

Yesterday,in an effort to save money,I called my water softener guy about that resin CR sells for 225.00 per cubic foot.Lo and behold the exact same product can be bought for 125.00 from him. Needless to say Im done buying that expensive resin from California. I bought a bag and used it....same results on the meter and no spots.

 

Resin Depot - http://www.apswater.com/shopexd.asp?...eionizer_Resin

Free UPS shipping when able to ship via UPS and is in the continental USA