This car has daytime running beams. Problem is at night the low beam is dim or dullish..hi beam is not bad but not great.
The lens are clear and I've replaced the bulbs. I'm not sure what to think is the problem. If I hold the Hi beam lever on the brightness is reasonable at night.

 

Make sure the electrical connectors at the headlights bulbs are not burned.

 

Does your car have headlight auto leveling? Maybe the motor went bad and light pointing downward.

If you don't have auto leveling. Then it is possible ... you had the bulbs installed upside down and didn't realize there was a locating notch on the top. It would make a difference, it's night and day. Once you flip them around, they will work great.

Also check 'dirty' terminals on the plug in...cleand them up, used a little di-electric grease.

 

Thanks for the tips..I had the problem since I bought the car 5-6 years ago. It was in storage than and I have not used it in a couple of years. I will check it out when I pull it out of our storage in a couple of weeks.

 

C4s were notorious for dim headlights. 2 ways to improve them... One, get an euro lens cover. Found here.

ECS Tuning

Two, people have been installing HID conversion kits. DDM has good reputation.