Is there a difference between diesel fuel used in cars and furnaces?

Yes, the home heating fuel is of a lower quality or cetane rating than that used for an automobile.

also home fuel is not taxed thats why it is dyed red so they cant sell it for autos it will run fine. cetane booster is 4 bucks. by me truckers are tested for red fuel. dont even ask what the fine is many people have 500 gallons in a above ground tank and fill there car as needed at a 1.50 less a gall. cars are not tested in nj so makes you think youcouldnt tell the difference in performance or smoke just color