L6e-BP micro EV structure Unibody vs plastic frame structures L6e-BP electric microcar L6e-BP quadricycle structure Unibody micro EV Plastic frame electric quadricycle EU L6e-BP structural engineering L6e-BP type approval structure Unibody vs plastic frame in L6e-BP micro EVs Structural engineering in L6e-BP vehicles Dealer risk L6e-BP micro EV EU compliance micro EV structure L6e-BP electric microcar microcar electric quadricycle quadricycle urban electric vehicle electric vehicle city electric car electric car compact electric vehicle low-speed electric vehicle EU homologated EU homologated electric car EU homologated electric quadricycle electric car for city commuting electric vehicle for short distance travel small electric car for urban areas compact EV with large boot electric car for daily errands affordable urban electric car Citroën Ami alternative Fiat Topolino alternative Aixam electric alternative L6e electric vehicle manufacturer electric quadricycle supplier electric microcar manufacturer last-mile electric vehicle PMSM motor AC induction motor electric vehicle motor L6e electric vehicle micro electric car EV motor efficiency