n00b DIYer

Yes; on most modern cars—even those made in the U.S.—you’ll find only metric fasteners. Toyota typically uses Japanese Industrial Standard (JIS) wrench sizes: 8, 10, 12, 14, 17, and 19 mm across the flats, plus a few larger sizes.

I just posted a list of what’s in the latest standard tool set from Toyota. I wouldn’t suggest buying one (unless you’re in Japan and getting the trade discount), but I think the list of tools is a good starting point, with two exceptions: for 2010 and later Prius cars, you’d need only the 14 mm spark plug socket, not the 16 mm, and the air duster is useful only in a shop with an air compressor.

I’d suggest a few other items, such as an oil filter wrench (64 mm), an inexpensive digital multimeter, a set of molding removers, and at least one torque wrench. An inspection mirror (with magnetic pick-up tool) and flexible spring claw are also convenient. Your tool kit isn’t complete, of course, without safety glasses, work gloves, and disposable gloves, for yourself and any helpers.

 

You’re most welcome.

That’s reasonable, but you can make substitutions, of course. For example, two sets of combination wrenches would work almost as well as the double open-end and double box-end wrenches in Toyota’s set. The main idea is to have two wrenches of each size and type, one to turn the nut while the other holds the bolt head, or vice versa. The long offset wrenches give more leverage to loosen stuck fasteners, though.

The government’s Use and Care of Hand Tools and Measuring Tools (PDF) manual (USAF TO 32-1-101) has more good advice; it’s written as an introduction, but even experienced tool users will learn a few things.

I don’t have enough experience with the tools being sold today to recommend for or against specific brands, especially with the recent changes in the hand tool business. In general, I wouldn’t suggest buying a large set with many tools you’ll never use, or that are so poorly made that you risk damaging the car or injuring yourself.

Besides hand tools, you should also consider getting a Toyota Techstream diagnostic system, since generic OBD II scan tools sold for engine and emissions diagnosis typically can’t communicate with many of the computers on Prius cars. Together with access to the Repair Manual (more info), this will let you diagnose most problems. Even if you sometimes need to have a dealer or independent shop do the repairs, if you know what has to be done, why, and how soon, you’ll be in the best position to keep costs down.