Slaapman

"Vehicles can also be customised. Customizations include paintjobs, wheels, window tints, grills, spoilers, along with robust performance upgrades to suspension, engine, brakes, and more that make meaningful changes to the way vehicles feel and handle."

The Car Custamization is on par with Midnight Club Los Angles.

Yes, there will be, and to quote Rockstar Games "Without going into detail just yet, we can tell you that both [vehicles and weapons] will be very customizable – with a range of weapon upgrades as well as some very deep car customization. Stay tuned for more very soon."

[] = my edits

I hope so, that was a pretty cool part of San Andreas but I guess it's not for everyone.