550k is a low combustion temperature. “Modern military jet engines, like the Snecma M88, can see turbine temperatures of 2,900 °F (1,590°C).” https://en.m.wikipedia.org/wiki/Turbine_blade
Absolutely. But I read the comment as complaining about efficiencies of automobile engines, not modern military jet engines. The combustion temperature of gasoline is 553K.
That’s like ~1850k assuming 2900F was rounded.