I had good luck with Mothers Headlight Restoration Kit

[BrianKK]

The Mother's headlight restoration kit was on sale at Autozone for $10, so I picked one up.

I was skeptical that it would work, but so far, so good.

The kit included some rubbing-compound-like liquid and an attachment for your drill.

before:

headlight lens before by ChurchOfBK, on Flickr

after:

Headlight lens after by ChurchOfBK, on Flickr

It's only been a week, so who knows how it will last, but initial results are good.

Just FYI.

[aterry1067]

Impressive! I usually use 1K grit wet-sand, buffing compound, and then Royal Blue (or any other good quality polish). But for $10, you can't beat that. The drill attachment alone is worth that. Looks like I'm headed to AutoZone tomorrow, and hope it's still on sale.

[BladeRunner919]

Nice work! I used the 3M kit with similar results - it's amazing how much it freshens up the front of the car.

[Vintage42]

I wonder what causes the plastic to become cloudy. Abrasive scrubbing, cleaning with the wrong chemical, hot sun, ozone? My car was built in 10/96 and its plastic is clear as new.

[Kram71]

Very nice job. It made a significant difference.

[poordna]

I bought the 3M kit, very inexpensive and quite effective. I'll never trust the kits that just provide like a wax coating or something that needs re-application.... I used the 3M resto kit but then went over it with clear coat

[RedRedZ]

I wonder what causes the plastic to become cloudy. Abrasive scrubbing, cleaning with the wrong chemical, hot sun, ozone? My car was built in 10/96 and its plastic is clear as new.

It's my understanding the polycarbonate is affected by heat from the bulb, UV rays from constant exposure to the sun, and abrasion. Keep the car indoors, cool and don't use the lights and they will last a long time. Daily drivers will suffer the most.

[KillerSE7EN]

It's my understanding the polycarbonate is affected by heat from the bulb, UV rays from constant exposure to the sun, and abrasion. Keep the car indoors, cool and don't use the lights and they will last a long time. Daily drivers will suffer the most.

This is on the money, the poly-carbonate is covered in a sealer that eventually wears out and becomes oxidized. I personally like a few products: the 3m kit that comes with the drill attachments are a great professional substitute, Crystal View is a nice professional kit, and Meguires plastx is great for removing oxidation.

Jordan

[BrianKK]

To update the thread, as I had feared, this was a temporary solution. The lights have a heavy haze again.

It should be noted that my car is parked outside almost all the time. Ahh the joys of a one-car garage and no way to permit an extension. :p

[fmcfad01]

Maybe hit them again with another kit and throw some lamin-x on?

I did this with my second hand OEM M5 headlights I bought off a friend for $200 and they look very nice. I've been hesitant to do my m coupe headlights because they look relatively good at the moment.

- - - Updated - - -

http://www.lamin-x.com/BMW-Z3-1996-to-2003-s/817.htm

[DYL]

You need some sort of UV protection coat. Lamin x should work. Some people mix urethane and mineral spirits and paint it on. I think there was a thread recently posted about special headlights clearcoat.

[Eurospec]

Applying a urethane is the way to go. And that is, after some serious elbow grease (sanding). Mine are holding up very well after about a year with an occasional plexus application.

Here's a thread I posted with the results: LINK

[Vinci]

If you keep the lights coated with sealant/wax, they also seem to cloud up much more slowly.

This applies with acrylic sealants, at least. Carnauba might not turn out as well.

[RossBMWZseries]

I suggest you do the same process again, but this time invest in some Lamin-X, it'll keep your lights looking like new for a really long time.

My lights on the Z4 are EXTREMELY yellow. I've had them done a few times but I was told that much of the haze went through to the inside and that nothing can be done now :/