well i went to my local trago mills the other day and whilst there i saw this thing you plug in to your cig lighter and on the other end it has a plug so you can plug anything in to it, i thought that was a good idea well for me it is as my hoover will not reach the car from my house, i did not buy one im thinking about it. has anyone else bought one?

What you seem to be talking about is a power inverter.
12VDc - 240V (Cigarette to 3-pin Mains).
I have a 150W one that i bought from maplin about 6months ago there good for running small devices, I use mine to power my laptop, Charge Cameras, 2-way Radios etc.
There good but you need to be carefull, they can drain you battery pretty quickly and leave you stuck in the middle of nowhere, trust me i know.
I have a 150w work lamp and decided to "try it out" on a camping weekend, it lasted <10min before cutting out and leaving my car battery dead. thankfully i got a jump and everything was OK again, The car battery is and was fine (had it checked) so i can only blame the inverter.
I only really use mine with the engine running now, charging my 2-way radios is ok thou they use a small amount of power so i can happily leave them for a couple of hours on charge or use my laptop parked at the beach for an hour or so (both with engine off)
I'd imagine a hoover would use a lot of power and may even require more than the inverter can give so be careful..

out of interest, mine was £14.99 from Maplin

you supposed to use them with engine running.

they wont power a hover, a hover is about 1500w-2000w

ok thanks for that its just i have not seen them before and thought it might be a good idea i didnt buy it.