On used cars is mixed. You need to pay taxes based on sell value, with a lower limit based on the blue book equivalent we have here. People just declare a bit l

On used cars is mixed. You need to pay taxes based on sell value, with a lower limit based on the blue book equivalent we have here. People just declare a bit less than blue book value and pay the minimum. But yes, most of Spain's submerged economy is via services without invoices (no VAT, no IRPF).