I originally bought the Criterion edition of this movie on DVD a few years ago. Evidently at the time it was a very good transfer.
Also at that time is when I learned the movie was originally filmed on 35mm film in the 2-perf format. Meaning, the resolution is half that of a movie shot using the "normal" 4-perf format.
Still, there are other films recorded in the 2-perf format that look much better on Blu-ray such as "The Good, the Bad and the Ugly." And that was an older restoration from about 10 years earlier that was transferred onto Blu-ray format. I believe that movie could look even better if given a proper transfer today.
The 2-perf format was used on a number of other films during that time period. The reason was good for movies with low budgets...simply, the 2-perf format saves 50% of the film costs.
Still, compared to what I saw on the most recent Blu-ray release of "The Good, the Bad and the Ugly," "Two Lane Blacktop" has a long way to go in the restoration AND transfer department.
It makes me wonder if they simply used the older transfer and simply used that for Blu-ray?
I will say the quality of the still frames here... http://www.blu-ray.com/movies/Two-La...Blu-ray/30765/
look much better than the frame shots posted earlier in this thread.