Considering the growing effect of gas prices these days should automakers be allowed to lie in their advertising any longer?
They aren't liying. The figures they give for mpg are real, under the conditions specified, which have to be the same for all vehicles being tested (a constant 56 mph, and 'urban cycle', for example).
Of course, they may only explain the test conditions in very small print, but these are real fuel consumption figures. As has been mentioned, the fuel figures are only really there for comparison. You should no more expect to be able to match exactly the consumption figures shown in the brochure than you should be able to match the maximum speed figures - measured, as they are, on a closed speed circuit with a perfect road surface and a car in showroom condition. (Speaking for myself, I routinely get higher
mpg than my car was advertised at, as well as lower, depending on where I am going, under what conditions, and the way I drive to get there.)
But this whole question misunderstands what advertising is for - it is there to make you want to buy the product or service in the first place, and to make you feel good about having done so afterwards (marketing textbooks will tell you that this latter function - combating 'congitive dissonance' is the main function of consumer car advertising).
It's like a dating service. Are you going to post a photograph of yourself with spots and a beergut having just got out of bed after a heavy night, or one of you smiling, well groomed and looking your best? Provided you aren't doing what lots of online daters do, and positng a photo that's 15 years and 60 pounds out of date, both are telling 'the truth', or at least an aspect of it.
And if you're surprised that advertising shows its products and services in a bad light, you really are going to be devastated when I tell you what bears do in the woods... Should real world gas usage statistics (averages) be used and represented during talks about increasing the fuel efficiency of cars in relation to rising energy costs?
Whose real world?
Someone small who drives alone over long distances on empty roads in an unladen vehicle?
Or someone large and heavy who takes all six of their large and heavy family with them, along with their luggage and some shopping, while towing a trailer, and stopping & starting on multiple short trips through rush-hour traffic?
Or somewhere in between? What, specifically, should the "real world" conditions be