it can go either way imo. using the term dd to me means that hey i drive this car...its not a weekend fun car or something that gets driven occasionally. i think that some have a pretty heavily modded car that is their only car and use the reference of dd in the fact that yeah i drive this daily whereas most won't/wouldn't. i use the phrase this is my dd when talking about mods and saying hey this has to be reliable this is my dd....well as reliable as a modified car can be lol.