im glad you brought that up, theres no point in filming just your speedo which endless people will because it visually looks s**t if left on the screen longer than 2 seconds
Quite right too.
I really wish I had the funds to do video but to do it properly you have to spend decent amounts money.
Some of the effects on that Topgear vid have been added digitally, but alot of it is special camera lens filters, and wideangle, fisheye lenses.... feck knows how much that stuff costs. Then a decent G5 pro, big hdd and ruck of memory to edit it all on...
I can't stand speed clock vids either unless, like you say, it's brief and you can hear and see the vehicle doing somthing impressive getting to 70 in like 5 seconds otherwize it's yawnsome; I posted a mustang one up a fewdays ago and the driver must have been going past a row of trees while it was filmed so you got this rapidly accelerating strobe of sunlight across the dash each time he passed a tree.