I've got 4 pieces of 8 x 8s that are about 24-30 inches long. These are what I use on any of my cars, with ramps up front, if I need to be totally underneath doing any work. Most of the time I'm using a pair of Rhino ramps I have up front for oil changes.

But I also have a set of metal ramps that I can remove the inclines after getting the car totally up. Helps when I want to work from behind the front wheels (e.g., tranny oil change). But for the Crossfire and my 2012 Fiesta, these metal ramps are too steep an approach angle to use with these cars. So my Dad many years back, made me a pair of wooden blocks that change the approach angle for these metal ramps & now I can use these on any of my cars. Ramp height is much more on these than the Rhinos and gives me more room to work under the car.