mpg, nightime driving vs daytime driving

The technical term is "density altitude." Start off with an already high field elevation like you have in UT, then add a hot afternoon, and density altitude will exceed the lift capabilities on some aircraft. Or at least require an extended takeoff roll and slow climb rate. The ones that crash during the summer are usually those guys that fill all four seats in their 172 with adult passengers, full of fuel and think weight/balance work is just stuff you have to know for the exam.

I also did some training and did manage to solo. Got into a bind on time and money and decided on other priorities. Fortunately my training was at KPDK (north side of Atlanta), with a field elevation around 1,000 ft and the smallest runway 3000 x 75. About the only small aircraft to fall out of the sky were cheapskates taking off with low fuel trying to get to a rural airport and save a few bucks on a fill up. Kind of a Darwin thing going on there.

I think air density is a factor in nighttime mpg, but probably more about having less traffic in the way to ride the hills better.

 

When I was 16 where I lived the law dictated that we could only own motorbikes with 3 cubic inches displacement maximum (When you turned 18 no limit).
Although not legal or advisable we would sometimes give a friend or 2 a lift on the back roads.
It goes with out saying that these sewing machine motors were always at 100% load.
There is no doubt that on a cool night they performed noticeably better.

 

Also, hotter roads means softer tires. More grip, more traction, higher rolling-resistence.

 

Watch NHRA Drag Racing. The Top Fuel and Funny Cars can tune for most anything.

But the normally aspirated Pro Stock and the Bikes are much slower when it's HOT!

Almost all GREAT runs are made at night....

 

Also - cooler air flowing across the CAC.

My 3406C is one gear difference on steep long hills with max load when it's 95° vs 65°.

 

As usual...Red is correct!

My brother-in-law, having just received his pilots license...decided to take his wife, her best friend, and her boyfriend up to Tahoe for a "celebration dinner" departing from Sacramento. In a Cessna 172...after dinner returned to the South Lake Tahoe airport, (had the planed fueled while they were dining)...attempted to depart, and could not get enough speed to lift off. Returned to the flight center and asked why this was happening....the guy looked at my BIL and laughed. As wifey, best friend and boyfriend rented a car and drove back to Sacramento....Chris had no problem flying home from Tahoe with 450 pounds less on board!

 

I'd say night driving has a positive impact in a bunch of ways.. from cooler air for better (if any) fuel mileage, road temperature for tires rolling cooler, engine working at 100f less degrees than during the day, no traffic, closed scales and others I can't bring up at the moment.

 

Don't forget, you tend to also drive slower at night because you 'feel' like you're going faster due to only seeing a bit of road in front of you. I know I always tend to go about 5mph or so less at night than during the day. Yet I feel like I'm always driving much faster.