My father had a '66 Rambler Ambassador that he used to pull a 22' long offshore fishing boat for a couple of years. It had the 232 cu in 6 cylinder, manual steering and manual brakes and would make 55mph on level ground flat on the floor but it made several 400 mile trips to the coast for him. The '69 Newport with a 383 and trailer tow package was a major upgrade.
My brother's 1970 retired state police Javelin with a 390 was quite a different animal. The police used to say that it could catch people going 160mph. Considering that he owned it in the late '70s when most cars couldn't hit 100mph it was quite exceptional.