Diesel
 

Seems I recall reading about a guy in California that swapped a Kubota diesel into a Metro and he got 95 mpg ..............

Looks like one of the chinese yanmar clones. This must be the kubota. Hell yeah!

96 mpg
 

Years ago in a publication called Diesel Car Digets there was an article that told about a conversion using a 1970 Mazda R-100 and a Kubota 2 cyl diesel with a Toyota 5-speed transmission that would reach freeway speeds, rather slowly, and got 96 mpg to a gallon of diesel. The publication date was around 1974.

A smart cdi engine in an aerodynamic and light car like an Insight would be a nice combo.

It's possible to get 104mpg in a civic vx if you only go 20mph, or 116mpg in a metro xfi at the same speed.
Road And Track Article
If I want to get 128mpg at 35mph I'll ride my moped, sure 85mpg at 55mph would be nice compared to the 65mpg that my motorcycle gets going that speed, but what's it get at 70mph freeway speeds, if it even goes that fast?

Provided it goes that fast, probably high 60s. I dunno why anyone who's interested in efficiency would go faster than 55-60mph on the freeway...

some people like to go over 65mph on the interstate to save time, or to keep from being run over, I know I've enjoyed my civic vx being able to merge on to a buissy freeway with 5 adults in to car on a number of occations, I also have ridden in vehicles that are governed to cut out the engine if you try to go over 85mph for more then about 5 seconds, to me it would make sense to drop that down to 80mph or so.
It's not very safe to drive alot slower then everyone else, I think being rearended is still the most commen form of trafic acident, and car accedents are the most commen way to be killed.

I dunno where this fear of being rear-ended comes from... Just stay on the right where you won't get people going 85mph up your butt. Iirc, 80% of all traffic fatalities are due to drunk driving and run off the road accidents, and even then I'd rather being going 55mph and have a drunk rear end me than go 85mph in the same situation. Braking distances are proportional to KE, and go like V^2. So at 55mph I can come to a stop roughly 2.3 times sooner than at 85mph, which is a lot of real estate I'd rather not cover in a panic situation given the choice. Merging is just a matter of checking your mirror ime, but I guess people feel more secure with more power?

Idling in 5th my car (diesel) runs about 28-29 mpg and SG indicates between 120 mpg and 180 mpg. Some day late at night I will try driving home that way ;)

This will go no where but...Briggs and Stratton makes nice little diesels. The price will scare you.

https://www.tulsaenginewarehouse.com/...47-580447.html

There are a lot of small diesels around but you need to get the engine at salvage price to make any sense of any conversion I could come up with.

Did you follow the earlier omgwtfbyobbq link to this link? This is one cute little bugger.

https://www.canadiandriver.com/articles/gw/vw1litre.htm

I need to figure out and copy that front wheel treatment. If Boeing can go 500 mph wihout covering up their wheels I ought to be able to go 1/10 of that. Some planes don't completely cover the wheels when retracted.