Flat Out Achievement in Forza Motorsport 4

Can someone define "perfect speed" ?

Full speed?

No its not full speed because I just got the achievement at 230mph. I was going for the 240mph achievement using the Bugatti Veyron on a LeMans Track when I got it.

Car: Any car that can go over 200 mph Track: Indianapolis Motor Speedway (Brickyard) Mode: Freeplay, timetrial You only need to go over 200mph for about 6 seconds !

This can be done in any car, i did it in an f class chevy on le Mans, I think the one that says old or something. All it requires is to have quite a high speed for a while, I think I was going at about 90 ish i think, although it's probably easier in the veyron, as it can get you Speed Demon at the same time.

this is actually somewhat logical. get as close as possible to the top speed of your particular car. just take whatever car you want onto one of the high speed tracks. I did it on sedona raceways full circuit, in my starion at around 126 mph. managed to get 6 'perfect' speed ratings on the track over two races.

It's time based not speed based. Or at least, not entirely speed based. Hit 220+ MPH and stay at that speed until the achievement unlocks. Less than ten seconds so choose Old Mulsanne and get a Koenigsegg CCX or something.