because it's got an engine smaller than 1300cc and total weight under 1 tonne?

or maybe because they're making a lot of them with diesel engines now, and many states STILL ban them in private cars because of how smoky the old 60s/70s ones were....
and..... i thought the kia pride was itself an old 121?
too bad they didn't import our fiestas really, apart from the gutless zetec i learnt in i quite like them, particularly the old ones. some genius went into the original design i reckon, and it's ebbed away since... they'd have probably sold like hot cakes, and they'd be "all american" too (especially with the low-revving, pushrod engine) rather than overly fizzy rebadged imports
4 door yaris......? you mean.. 4 door hatch.. or, as im dreading, some kind of awful USA-only saloon bodge job?
(to interweave subjects, i saw a saloon version of the more up-to-date mazda 121 in a bournemouth car park.... why did they bother? it looked a mess and you probably couldnt get a full weeks shopping in the boot)
edit - the smart car thing could be because of it's retarded three-bolt wheels. i'd happily ban them for just that reason.