Your typical car only uses about 20-30 horsepower when going down the road. However when coming off the line at a light it can use hundreds of horsepower for the 3-10 seconds it takes to get up to 60mph (for non-US readers, in the US all car reviews make a big deal of the 0-60mph times, and many magazines have tracks where they test that themselves. I'm guessing you would see 0-100mph here, which is only a slightly different top speed by I have no idea). Thus for car applications a motor that can deliver a lot of power for a short amount of time is useful and light weight is important. If this is light enough it might be worth the unsprung weight issues to put this in the wheels (particularly front wheels to get cheap 4x4)
Automobiles are rather unusual in wanting and using a high amount of power in a burst and then needing a much smaller amount most of the time. Most equipment (including trucks when used as a truck) tend to need a lot more power all the time.
