Not at all. Mejor is better Mayor is bigger Nit the same asjective

Yes, 'mayor' is bigger, not big, and mejor is 'better'. Take care, Alejo! REF.: I'm a Certified Spanish Teacher

To me "este coche es mayor" sounds weird, I think I will never say that about a car. I would say "este coche es más grande". If you use it it sounds like "this car is older" rather than "thid car is bigger". Cheers!

well... let's take some examples una persona mayor = an elder person un problema mayor = a major problem yo soy mayor que tu = I'm older than you so finally you can notice "mayor" has the feeling of "superior, older, bigger" For me, saying "este coche es mayor" sounds a little bit weird, like, you are comparing two cars and one is older.

Este coche es mejor = This car is better. Este coche es mayor it meas = This car is big. Saludos.