Unless it's Lexus & Toyota dealership like my local one (two separate showrooms side by side, but share the parts counter & workshops too when needed). You're unlikely to get your IS250 serviced at Toyota. Toyota UK never had any cars with this engine etc. IS300h for example is essentially a smaller Camry and RAV4 uses the same engine too, blahblah. Bottom line, they have parts and they're cross-compatible. IS250 was solely a Lexus car built on a Toyota Mark X platform but that's Japanese model only, so again, Toyota UK is highly unlikely to service this particular car because they probably wouldn't have parts.