I emailed the staff in English twice and they responded within 24 hours. You can ask them specifically about car model etc. The actual onsite staff cannot really speak English, so it's best to ask all of your questions via email before you go. (I guess there are some staff in the central office that can read/write english well and they handle all the emails)
Renting from this website is more expensive than renting via tocoo, but they have better staff support for non-Japanese tourists.