Recommend a IoS speed alert app?

[AMG Merc]

Hi, I'm looking for a simple Apple app that displays the speed as large as possible (that's all I need it to do. Any suggestions appreciated.

[Mr E]

I've used SpeedHUD when the speedo in the lotus was playing up. Free. Simple.

Also fun on trains when the child wants to know how fast we're going.
Doesn't work very well on aircraft.

[Huff]

Speedometer (free) works well, can set your own limits (up to four) etc which changes colour of display and (if your phone connects to car via bluetooth) the beep - if set - will get played over audio system. Large clear green on black display too.

[AMG Merc]

Thanks guys. Think I've downloaded Speedometer - seems to work well. Can see any settings options but I've the free version right now.