iOS 7.0.4 / iPhone 4s problems with bluetooth handsfree car connection

We purchased two unlocked GSM iPhone 4s at the same time two years ago.

They came with iOS 5, were upgrded through the various iOS 6 versions.

Through all of that, both phones worked perfectly

with our two (2006 VW a5g, 2008 VW b6)

VW factory bluetooth handsfree systems -

both are the VW 9W3 premium (one rev 0, one rev B)

that integrates with the cars multi-function display and

steering wheel controls. (Not the basic Volk-L handsfree kit.)

This is what it looks like when it is working correctly.

For two years, never had a problem, both phones and

both cars handsfree bluetooth systems worked perfectly together for hours on end.

Until iOS 7 was put on my iPhone 4s.

My wife's identical 4s hardware remains in iOS 6.1.3.

We took a trip together early November in the 2008 VW and

used the many hours in the car for the passenger

to test and confirm the current function of both phones.

The iOS 7 bluetooth function / malfunction is

very repeatable on two different bluetooth connecton samples.

Since installing iOS 7, the car and the phone still automatically connect as before.

For about 2-5 minutes after connection, it still pretty much works as before,

the MFD displays the phone information, calls do work as before.

Shortly after connection, exchange of display information deteriorates first.

Within 5-10 minutes, the bluetooth connection becomes unusable and then drops.

Even without use, the connection drops in 8-15 minutes,

and for a short period before it drops, it is unusable.

It can be reconnected after a drop by cycling bluetooth off and on

and it will work for another cycle.

Of course that is not practical when driving alone and the phone rings.

This behaviour is practially identical on both cars with the

iOS 7 iPhone 4s (all updates from iOS 7 through 7.0.4).

My wife's iOS 6.1.3 identical iPhone 4s hardware

continues to work perfectly with both cars.

I have no other issues with iOS 7 on the 4s,

phone function, data service, WiFi, GPS, battery life, etc

continue to work acceptably.

I keep hoping this bluetooth issue will get addressed in one of the updates,

but four updates and nothing has changed.

Am I alone with this issue?

I upgraded to iOS 7 for the improved security functions,

but giving up a useful bluetooth car connection is not worth it.

Gee Apple, if it ain't broke, don't fix it. Wish I could go back to iOS 6 ...