Petrol and diesel cars are powered by heat engines (internal combustion engines). ONLY 30-35% of the combustion heat is USEFUL
So about 60% of the fuel is just WASTED HEAT and useless energy, which is unavailable for powering your vehicle and just goes to increase the disorder (see ‘Entropy’) in our already disordered universe.
The key parameter is the temperature difference between the input and exhaust gases. I suppose that if you modified your car so that it ran at cylinder-melting temperatures in a Canadian winter you just might increase the thermodynamic efficiency by a few per cent.
But with fuel prices in the UK now at about £2.00 a litre, you really are wasting £1.20 a litre!
The internal combustion engine is rapidly becoming obsolete outside of residual niche markets such as very large lorries or for railway locomotives hauling freight in widely dispersed countries like US, Canada or in Africa.
Google “Carnot” and/or “Heat Engines”. Study physics!
If you are intrigued by historical forms of locomotion, visit a heritage railway. (pic BBC)
Yes, a steam engine is an external combustion engine but the heat engine efficiency limits still apply,