Wait.....on the first example, it would probably help if you asked the person more info about their car, first; it comes off as arrogant because you are assuming they don't know what you're about to impart on certain assumptions (such as a new car) that may be false. I, for example, have two seventeen year old trucks that exactly benefits from a good occasional coast.
In fact...the other problem of the first statement is that it's a sort of "Let me tell you" without engaging the poor person with a tactic that doesn't sound preachy. If you said, "Hey, I read that new vehicles with X engine no longer gain a performance benefit out of Y action, boy that sucks, eh?" it would be friendlier without being too snotty.
To be honest, I might have fought you with that info....or questioned it, anyway, since that's news to me!!! (But hey, I drive two 17 year old trucks, so whadda I know). In fact, I've never heard of any state that has laws against it, either (in the US anyway). I'd be torn between wanting to ask for more details, and removing myself from the conversation to look up these facts later, because I wouldn't want to reward the arrogant soul who just decided to "elucidate the poor misguided fool." Sigh....egos....tough things to deal with on all sides.....
EDIT: Ah, forgot to mention! I'll correct people on details I consider myself a reasonable authority about (say, archaeology or accounting, two subjects near and dear, or just near and near to my heart), but like I said, I prefer not to do it in a manner that implies anything about the "corectee" in the manner. I know I hate that when people do it to me...and the only ones I meet who engage in such behavior almost inevitably come off as pompous or arrogant.