I saw a strangely configured IS300 sitting parked near mine this morning.

It was Ultra White....had the black mirrors like the Black Line Edition.

Had the bumper-integrated exhaust tips.

But it was not an F-Sport.........had the 5-spoke wheels.

Had the non-Sport grill, but the grill was black.

I just guessed it was not modded because of the black mirrors.

Maybe a simple mirror/grill switch. Strange mod to put black mirrors on the Ultra White.

Caught my attention.

 

The white / black contrast is quite common. Could jsut be a bit of custom vinyl wrap work?

Subtle mods go a long way and maintain factory like clean look.

 

Just to note, the Black Line edition comes in Ultra White.

 

If it were a true Black Line Edition, it would be either in obsidian, UW, or atomic silver. The non F-sport front grill and the 5-spoke wheels makes me think the car you saw was just slightly modded. Here's what the BL edition includes for the IS300 stock, per Lexus:

2019 IS 300 AND IS 300 F SPORT AWD BLACK LINE SPECIAL EDITION

Fusing edge and exclusivity with obsessive performance, this is the 2019 IS F SPORT Black Line Special Edition. Limited to 900 vehicles, this unique edition combines upgrades like Premium Triple-Beam LED headlamps with exclusive features such as sleek, black outside mirrors. And complementing its aggressive stance are 18-inch split-five-spoke F SPORT alloy wheels* with a Black Vapor Chrome finish. Inside, you’ll find a Black interior trim with a heated steering wheel as well as Black NuLuxe®*–trimmed seats with red accents and stitching.
2019 IS 300 AND IS 300 F SPORT AWD BLACK LINE SPECIAL EDITION FEATURES

18-inch split-five-spoke F SPORT alloy wheels* with Black Vapor Chrome finish
Black NuLuxe®–trimmed seats with red accents and stitching
Black tone-on-tone heated wood-trimmed steering wheel
Black tone-on-tone interior trim
Black outside mirrors
Ultra White, Atomic Silver or Obsidian exterior paint


INCLUDED OPTIONS

Premium Triple-Beam LED headlamps
Lexus Navigation System*
Blind Spot Monitor* with Rear Cross-Traffic-Alert*

 

I've seem the "blacked out mirror" mod on ultra white combo a ton with BMW's, Audi, and VW.