▁both ▁the ▁Low ▁F loor ▁and ▁the ▁In ver o ▁lines . ▁ ▁Design ▁ ▁For ▁example , ▁a ▁New ▁Fly er ▁D 4 0 i ▁is ▁a ▁ 4 0 ' ▁( nom inal ) ▁rig id ▁In ver o ▁with ▁dies el ▁power . ▁New ▁Fly er ▁never ▁officially ▁produced ▁any ▁dies el - elect ric ▁hy brid ▁In ver os , ▁nor ▁did ▁they ▁produce ▁any ▁art ic ulated ▁In ver os . ▁ ▁Work ▁on ▁what ▁would ▁become ▁the ▁In ver o ▁started ▁in ▁ 1 9 9 7 . ▁A ▁prototype ▁In ver o ▁was ▁first ▁shown ▁at ▁the ▁October ▁ 1 9 9 9 ▁AP TA ▁trade ▁show ▁in ▁Or lando , ▁Florida . ▁A part ▁from ▁the ▁more ▁stream lined ▁exterior , ▁other ▁improvements ▁over ▁the ▁existing ▁Low ▁F loor ▁models ▁included ▁larger ▁windows , ▁improved ▁he ating , ▁more ▁seats , ▁easier ▁maintenance , ▁and ▁the ▁use ▁of ▁composite ▁materials ▁to ▁reduce ▁weight . ▁The ▁driver ' s ▁wind sh ield ▁has ▁been ▁sh aped ▁to ▁reduce ▁g lare . ▁The ▁air ▁condition ing ▁unit ▁has ▁been ▁moved ▁to ▁the ▁front ▁roof ▁of ▁the ▁bus ▁to ▁allow ▁for ▁additional ▁passenger ▁seats ▁in ▁the ▁rear ▁of ▁the ▁bus . ▁The ▁resulting ▁elev ated ▁front ▁roof line ▁has ▁led ▁some ▁operators ▁to ▁affection ately ▁dub ▁the ▁In ver os ▁the ▁" Bel uga " ▁bus , ▁after ▁the ▁Bel uga ▁wh ale . ▁ ▁Fin an cial ▁difficulties ▁delayed ▁the ▁development ▁of ▁the ▁production ▁In ver o