We found the stencilled concrete very slippy in winter (we lived in the Chilterns & the drive was a steep hill). Also the sealant is a solvent based fluid that I think gives you an exposure to chemicals you don't really need.
My drive has a 1 in 2 slope, 10 metre drop over 20 metres. Yes you really need the ground up glass in it, it makes a huge difference. The first time I sealed my driveway I got a headache from the stuff, the stuff I use now is probably still solvent based but I didn't notice any smell or headaches at all.
Nice car, is it black or very dark green?