▁ ▁They ▁are ▁not ▁to ▁be ▁confused ▁with ▁purpose - built ▁for ▁racing ▁or ▁speed ▁records ▁fully ▁f ared ▁vehicles ▁with ▁two ▁whe els , ▁generally ▁called ▁stream lin ers . ▁Stream lin ers ▁have ▁set ▁many ▁speed ▁and ▁distance ▁records . ▁Though ▁fast ▁in ▁their ▁own ▁right , ▁vel om ob iles ▁are ▁considered ▁much ▁more ▁street able ▁machines . ▁ ▁Using ▁three ▁or ▁more ▁whe els ▁can ▁have ▁advantages ▁for ▁every day ▁use , ▁including ▁the ▁ability ▁to ▁stop ▁and ▁start ▁una ided , ▁better ▁stability , ▁cross - wind ▁handling , ▁etc ., ▁though ▁there ▁are ▁arguments ▁made ▁that ▁the ▁multiple ▁track ▁machines ▁( three ▁or ▁more ▁whe els ) ▁have ▁aer od ynamic ▁dis adv antages ▁due ▁to ▁the ▁drag ▁of ▁the ▁extra ▁whe els ▁and ▁the ▁surface ▁contact ▁points . ▁ ▁In ▁practice ▁though , ▁vel om ob iles ▁continue ▁to ▁be ▁close ▁to ▁their ▁two - w heel ▁c ous ins ▁in ▁performance . ▁▁ ▁There ▁are ▁few ▁vel om obile ▁manufact ur ers ; ▁some ▁are ▁home - built . ▁Some ▁models ▁have ▁the ▁operator ' s ▁head ▁exposed ; ▁this ▁has ▁the ▁advantage ▁of ▁giving ▁the ▁operator ▁un ob struct ed ▁vision , ▁hearing , ▁and ▁some ▁cool ing , ▁with ▁the ▁dis adv antage ▁of ▁being ▁potentially ▁more ▁exposed ▁to ▁weather ▁and ▁less ▁aer od ynamic . ▁Ful ly ▁en closed ▁machines ▁can ▁suffer ▁from ▁heat ▁or ▁hum id ity ▁issues ▁as ▁well ▁as ▁potential ▁noise ▁issues . ▁▁ ▁The ▁typical ▁drive ▁train ▁of