I found this site and it has what appears to be some great ramps and other things that some of you do it yourself-ers may like. The extenders might be a good idea, gives you a gradual incline, and once the car's in position, you can remove them to gain side entrance to the underside of the car, and they say they're especially for the low to the ground cars like our Z's are.
Here's the web address:
67" XT Ramps - Car Ramps | Get your Car Up 10"! | RaceRamps.com your best solution for Lightweight Car Ramps!