small, alert, and sure-footed.

Um. You do know the Impala is a land yacht, right? Drives like a boat--a tugboat, not a cigarette boat. She's got looks and heart and legs, sure. But small--no. Quick--definitely not. Quick-cornering? Hahahahaha.

A grade horse would be fine, and more common than purebreds. The wild mustangs cowboys caught and broke to saddle were smallish and weedy, self-bred down from Spanish stock and adapted to sparse graze and harsh terrain.

Baby would translate to Fresian pretty well, but there weren't many, if any, around in the states in the 1800s. Other breeds that were popular but hella expensive were thoroughbreds and Morgans, either of which would map pretty well. Morgans are smallish, but long in the body and bred for carriage work, not riding. Thorougbreds are big, rangy, powerful, fast, and temperamental. They didn't do well in rough, rocky terrain and weren't used hardly at all as working horses in cattle country. But that's what I'd translate Baby to, if you can work out a way that a working cowboy can afford one, and keep its legs intact over the ground a cowboy rides. Grade is horse for mongrel, thus pretty cheap, and tough if not talented, and is probably going to be about your best bet.

Okay, while I'm being wildly offtopic--where's a good place to find a visual reference for the type of bridle that would be in use in the West in the 1830s? I don't think the picture is going to include the saddle.

serial:

there weren't many, if any, around in the states in the 1800s

It doesn't have to be typical, just vaguely plausible. It's magic, after all.

Quarter horses have been used as stand-ins before. They're sort of the western default. If you're going for magical, I still think the car maps best onto thoroughbred for the same qualites: she's high maintenance, and she stands out in a crowd of economical, ergonimic counterparts.

Quarter horses are my personal fave--a good cutting horse is a joy to watch.

I guess the impala only seems small next to the giants who drive her.

Yeah, Impala = boat. Parking one, well, I'd have to get used to it again. Turning radius, heh.

I love the Quarterhorse for looks but not as big as you would need to stand out like the Impala. I would map the Impala onto Friesian, Percheron, or [link] Yup.

Okay, while I'm being wildly offtopic--where's a good place to find a visual reference for the type of bridle that would be in use in the West in the 1830s?

Are you thinking of the cowboy era? There's no significant American settlement of the West until after the War, except for the settlers to the Pacific Northwest on the Oregon trail. The cattle drives started in 1866; Dodge City started in the 1870s.

To be honest, I have no idea exactly where this is set. Just when (1836) and Western. If I have to reconcile visually with one over the other, I'll go with Western.

BTW, according to the scary website that posted it, the JDM-JA-JP photo was a manip combining a photo of JDM walking down the street with some other guy and a photo of JA and JP walking down the street in Vancouver. I will admit it took me a bit to recognize JDM - I don't know if I've ever seen him in glasses before.

Would this help any, ita?