Being voltage driven, his light up only 1 LED, I think. For my speed up/slow down, what I want is something that you can pick up in peripheral vision (I'm even thinking quasi-HUD via reflection off a windshield film strip) where the green/red bars grow in an obvious way.

There are "thermometer" chip LED drivers than can switch between "dot" style and "bar" style. Takes a reference voltage or two, voltage input and high or low to a bar/dot select pin... Some chips to check out: U1096B, LM3914N, LM3915N.
A6275/A6276 for more generic driver w/ uprocessor-interface

/Michael