Hi Bill
I do not know where you have that stuff from.
But for sure your statements will not stand closer investigations.

John Smith got it right:
I regularly tow single seaters with an Opel Astra 1.6 (gaz) -
front driven - NO 4x4. Plenty enough power, the speed is limited not by
power, but by the stability.

I towed my single seaters in Cobra trailers (~850kg) first with
a Fiat Uno (1.6liter, 4cyl, 70hp, low first gear and best torque
at 3000rpm) over many European mountain passes without any
problems. On a very hot summer day cooling the engine might
become an issue even with a electric fan, if you are stuck in traffic
jam behind a slow truck. But you still as a last resort can open
all windows and switch the aircon to full heat :-)

Your second "full throttle" theory also is weak. The economy
at higher speeds (60mph) in general depends on the highest
gearbox ratio and that is true for gas engines as well and aero-
dynamics. Don't buy a car which you have to rev up to 5000
rpm to reach 60mph! Make sure you can do it in the highest
gear at not much more than the best torque (~2000rpm for
diesels and =3500rpm for gaz).

My actual Peugeot 307 HDi Touring cruises 120km/h (75mph)
with a consumption of 6l/100km (39m/g) or 8l/100km with the
trailer hooked on (29m/g). The longer the wheel base, combined
with low CG and good suspension (NO spring leaves!) tows a
Cobra trailer at 75mph without stability problems.

Sports cars have best torque at higher rpm than economic cars.
When selecting a car in general for towing, get one with an engine
with long stroke and high torque at low rpm and get a sleek
design not a square SUV with lots of aerodynamic drag, and a
weight 1000kg above a normal station wagon. Towing with a high
CG and short wheel base (SUVs) is also no good for stable driving
behavior!

DON'T BELIEVE CAR DEALERS
they just want to make you believe that you need for towing
at least 6 cylinders, 3 liters, 200 HP and 4x4 drive
That's just plain rubbish
Think economically &
do not overkill
and keep your daily running costs down
to be able to spend more money on the real topic: SOARING.

But if you are a millionaire - then you do not have to care.

Chris
________________________________________________

"Bill Daniels" bildan@comcast-dot-net wrote in message
...
Dan

Keep in mind that there is "data plate HP" and actual HP. Turbo diesels
tend to have high "critical altitudes" which is the highest altitude where
the engine will produce sea level power. On the other hand, normally
aspirated engines will only produce a fraction of the "brochure HP" at
high altitudes. To get adequate power at the top of mountain passes with
a normally aspirated engine, you must to buy more power than you need at
sea level.

Diesels have excellent economy at part throttle but only slightly better
economy than spark ignition engines at full throttle. This means that
even if you bought an engine with the capacity to produce 286 HP, the
power that you actually use is determined by power demand which is in turn
mainly determined by the overall weight of your rig and driving style. To
increase fuel economy, reduce weight and run at part throttle. All else
equal, buying a larger diesel engine has little to do with actual average
fuel economy.

Bill Daniels