Learn English – The car is pretty slick/sleek

Broadly, English accents are divided into two categories, rhotic and non-rhotic. All English accents were originally rhotic, and the R sound was typically articulated as an alveolar trill, in contrast with the alveolar approximant of most contemporary dialects. Non-rhotic accents began developing in the Middle English period, and were commonplace by the arrival of modern English, gaining popularity in southern England during the 18th century.

Both the British Isles and the United States, as well as Australia and other areas where English is spoken, have regions of both rhotic and non-rhotic accents. As Alex mentions, notable non-rhotic United States accents include coastal New England, New York, and old-style Deep Southern; the so-called "continental" or trans-Atlantic accent, characteristic of upper-class America through much of the 20th century, was also distinctly non-rhotic. Rhotic British accents are to be found in the West Country, as well as much of Scotland and Ireland.

From thefreedictionary.com:

15 Marked by full control over elements or subordinates; firm: tight management; a tight orchestral performance.

In music it usually means all members of an ensemble are playing together with rhythmic and harmonic precision. I think it's not much of a stretch to work from that meaning to the sense of something being remarkable or "slick".