I think the main advantage of the speed freeks list is in the numbers it can field, while one of the top UK speed freaks lists could be built using the ghazgkull list with the only difference being the supreme commander, other successful lists make use of the trukks + boyz mob as I don't think there is any other list which gives you 12 units for 200 points, where possible keep the boyz mounted as this will mean it will be almost impossible to firefight you (10cm countercharge plus 5cm dismount) use planes for harassment and dethkopta formations to boost activations
one particularly crazy UK build took 14 gunfortresses, seems silly but it won the Grand Tournament back in 2011
these are obviously general ideas, best thing is to have a play around on armyforge and look at some batreps to see how others play the list