▁third . ▁ ▁Similarly , ▁going ▁from ▁ 3 ▁whe els ▁to ▁ 4 ▁whe els ▁can ▁change ▁the ▁category ▁of ▁an ▁otherwise ▁identical ▁vehicle . ▁ ▁One ▁reason ▁for ▁the ▁varying ▁treatment ▁is ▁that ▁many ▁laws ▁are ▁older ▁than ▁w ides p read ▁use ▁of ▁power - ass isted ▁vel om ob iles ▁and ▁so ▁the ▁laws ▁were ▁not ▁written ▁to ▁consider ▁such ▁vehicles . ▁ ▁In ▁some ▁areas , ▁laws ▁are ▁being ▁re written ▁to ▁include ▁power - ass ist ▁vel om ob iles ▁and ▁to ▁harm on ize ▁treatment ▁with ▁nearby ▁laws . ▁ ▁DI Y ▁( do ▁it ▁yourself ) ▁vel om ob iles ▁With ▁a ▁growing ▁DI Y - community ▁and ▁an ▁increasing ▁interest ▁in ▁environment ally ▁friendly ▁" green ▁energy ", ▁some ▁h ob by ists ▁have ▁endeav ored ▁to ▁build ▁their ▁own ▁vel om ob iles ▁from ▁k its , ▁s our ced ▁components , ▁or ▁from ▁scratch . ▁When ▁compared ▁to ▁similar ▁s ized ▁commercial ▁vel om ob iles , ▁the ▁DI Y ▁vel om ob iles ▁tend ▁to ▁be ▁less ▁expensive . ▁ ▁Probably ▁the ▁most ▁built ▁vel om obile ▁k its ▁are ▁the ▁various ▁models ▁of ▁the ▁Alle w eder ▁made ▁from ▁pre fab ric ated ▁al umin ium ▁sheet ▁metal ▁due ▁to ▁its ▁afford able ▁price . ▁Some ▁vel om obile ▁manufact ur ers ▁offer ▁their ▁models ▁as ▁k its ▁for ▁self - assembly ▁( R ä der werk ▁Milan ▁M k 2 ▁+ ▁Milan ▁SL , ▁Bey ss ▁Go - One