I have limited search capacity at work but this is what I used (Bought it from local mob in Aus - gasweld I think).
Spot weld drill bit
I used it to remove both sills and front valance on my coupe.
Things to note when using any version (and why I chose this one in particular).
When starting, the bit tends to wander on the surface, but once you start it should work pretty well.
To combat this using the above bit, I drilled a hole all the way though the spot weld to enable the centre spike to sit on the hole. This seemed to stop the majority of the bit wander issues and wasn't too hard to tac closed the small hole when the panel was removed.
Second thing I liked about this bit was you can buy replacement bits and the centre spike can be removed and resharpend.

Hope that helps.


Bryan

You can get long shank bits to access those fiddly bits. I ordered a heap from the states. It was cheaper buying new ones than paying to get them properly sharpened.
They're not as easy to sharpen yourself as a standard drill bit.
I think I was paying about $15 each for standard shank length and $25 for long shank.

A $2- water spray bottle is also a good investment for keeping drill bits cool. I use one for certain tasks. Water's great, dirt cheap (~$1/tonne in Melbourne) and exceptional cooling capacity.

the wurth ones are certainly very good, so too are the snap-on tools variety.

Thanks for the fantastic response, I will probably go for all of them and give them each a run to see which is best. I use cutting oil on just about everything so I'll be sure to keep them slow and cool.

I suppose the recommended rpm range will be specified on the package.

I use Wurth brand Wurth. I used to make my own but the wurth ones out last most others. but any cutting bit will go blunt Quickly if you are too aggressive. OAN878 may have some ideas aswell i'm pretty sure he uses them daily in his job.

I would highly recommend this specific type of drill bit, brand i couldnt tell you. I have heard nothing but good about these bits, and i brought one myself was awesome, as Simon said, keep them cool and drill on a slow speed.
There was only really one thing I found could have been better with this bit, it was rather short (perhaps for more strength, i don't know) so for example when I was drilling the tie hooks on my ute tray, it was a little tight, still worked with a bit to clear but tight....
http://www.shoptoolsforpros.com/media ... ill-bit-dent-fix-1610.jpg



I havent had experience with these drill bits myself, however when i did the research on a spot weld drill bit there was nothing but comments on short lifespans and braking chipping teeth...
http://forums.rennlist.com/rennforums ... val-tool-advice-95343.gif

Another tip, keep them cool when drilling by using a slower speed. They have a fine cutting edge compared to an ordinary twist bit and can over heat and lose its edge easily.
We used to use the wurth brand in the panel shop.

good auto paint supplier,i got mine from VG paints GIRRAWEEN NSW. works great.
approx $30.

Be aware that there's a trade off between toughness and hardness with cutting materials. A harder/ faster cutting tool (spot weld, lathe, drill whatever) is often more brittle and more likely to break under shock.

If you can get a tungsten carbide drill bit it'll be hard as and be able to cut fast but once it's blunt or chipped you'll likely have to throw it away. If you can sharpen them yourself I think you're best off with a good quality high speed steel (carbon steel), especially if you're drilling with a hand drill.

Have a look at sutton tools, they have a decent rep. My Dad's (carpenter) still using sutton drill bits that are at least 20 years old. Their factory is just around the corner from my house to.