I think that for vehicle related welding, the 125v MIG with gas, and an auto helmet would be ideal.

Having done stick, with a regular helmet, on automotive metal, it's not pretty. And very frustrating. It's hard to start the weld within 1/4" of where you want it.
With the auto helmet, the welds will be exactly where you want it.
And with the MIG (with shielding gas, not flux core), the beads will be very sweet.

If I were to start over, I'd actually get the auto helmet first. It's the most important part of my set-up.

...and a good, powerful, 5" grinder. Flap-wheels are your friend! Mine's 12amp, can't do metal work without it.

You can rent welders, but the other stuff...

Oh, and beware 2nd hand welding equipment. There's often a reason it's for sale, and repair$ will scare you. Buy from a retailer that services. The lower-priced units (century/lincoln) are not really servicable.

[/soapbox] [/preachin']