How many miles should one expect from a 2000 ES 300 Lexus in excellent shape?

No telling if properly maintained! 500k is not unheard of!!

The rx300 has 2 known issues. The first is engine failures due to sludge staring around 80,000 miles and transmission failures starting around 120,000 miles. The engine problem can be avoided by using full synthetic engine oil and top tier gas. The transmission problem, unfortunately, cannot be avoided.

Seen many(in the dozens) with over 250K and still going strong. Several are one owner cars and yes the maint. has been kept up with.........that almost always helps.

I have a 2000 es 300 and I have 272,000 and runs like a champ had to put a coil on it he other day and running great again oil changes !