Here,in this image provided by Hucho,you can see from the upper two images that drag increases from Cd 0.091,to 0.14 when the wheels are added.A 53.8% drag increase.
The 1987 GM Sunraycer has been reported at as high as Cd 0.143,and as low as Cd 0.089 with full wheel fairings.
In his book 'The Leading Edge',Goro Tamai reported that full wheel fairings could reduce wheel drag by up to 80%.
Honda reported Cd 0.10 for their fully-faired (but exposed-wheel) Dream-2 solar racer
The Cambridge University CUER also reports Cd 0.10
NUON NUNA-3 thru 7 report Cd 0.07
