Could someone provide a guide to the trim level designations on autos. i.e. xl, xls xlt.
How do they affect performance, quality and or especially pricing of new or used autos?

That would be an enormous list. It all depends on the car maker.

You would have to go at it for each specific model.
Example:

Chevy Malibu (2008)
LT - Lowest model, least amount of equipment
1LT - next level up
2LT - 3rd level
LTZ - highest level
Hybrid - in its on category

General rule is the higher the trim level, the better the resale.
As far as performance... many trim levels can have different performance level... again it depends on the car.

Again example - malibu

LT , 1LT 2.4 liter
2LT 2.4 liter standard, optional 3.6
LTZ 3.6 standard, 2.4 optional

This applies to many things as well... each trim level has standard options, but some options can be added/upgraded.


So it can be a combo. Hope this helps.