Question
I have patchy brown blotches in my hybrid burmuda lawn it is confined for the most part to a 4ft x 5ft area next to my driveway that gets most of the run off from washing vehicles or heavy rains. Some small blotches in some other area just in random location no real pattern to the blotches!!!  

Answer
Could be brown patch, because of the blotches in other areas. Grab a few blades, and tug on it. If it comes up (breaks off) easily, with no roots attached, it is probably brown patch. Brown patch is a fungus. Use a good fungicide, or, use baking sod disolved in water. Spray the area and soak the grass and soil round it. If it is brown spot, I would spray the whole yard.An ounce of prevention. If it affects one area, it will probably get to others, eventually. I use the baking soda. It works better for me than the commercial fungicides, and doesn't harm my little critters that eat the bad bugs in my lawn and garden.
 You may have two problems. don't discount the possibility that something you are using on your car is poisoning the grass in that area. You may have to change car washing products, or move the car away from the grass area.
Hope this helps. If you feel I can help more, feel free to write.
Charlotte