There are two other possibilities for what could cause difficulty with your vision at night:
1. If you have astigmatism (a lack of symmetry in the shape of your cornea on the eye's surface) the effect of the astigmatism on your vision will be worse at night. As your pupil dilates, light entering your eye passes through a greater area of the cornea. If there are irregularities in the corneal curvature, it scatters the light somewhat which makes things look blurry.
If you already wear toric contact lenses (which correct for astigmatism) it could be that you need stronger correction for this at night. You may be able to get a pair of glasses to wear when you drive to help with this problem.
2. If your pupils dilate a lot at night, you may be seeing a ghost image refracted through the bevel along the edge of the contact lens. I know about this because it happens to me.
You should talk with your optometrist about your night vision issues and see what he/she suggests. Try to be as specific as possible for the doctor about what the problem is with your night vision (general blurriness, ghost images, dimming or loss of contrast, etc). That might help narrow down the problem. Good luck!
Poor night vision can be associated with certain conditions like Cataracts, Vitamin A deficiency, Zinc deficiency, Retinitis pigmentosa, Diabetes. You may try to seek medical attention about a distance lens in each eye for your night driving purpose, and better let your eyes be checked by an eye specialist for further eye conditions.