i have Sonic & Sega All-Stars Racing , should i still buy modnation racer?

[sepisfu]

okay i got sonic & sega all stars racing like a month ago, and my question is " is it a wise choice to buy modnation racers " i mean how many racing kart do i need.the only reason i am thinking about it is i can buy it for 25 bucks

can you let me know how is mutliplayer in modnation racers