Just a few general comments about lift. Coming into this discussion group from outside, as it were, I have been really surprised how no-one seems to pay much attention to lift.
In general, lift = drag. This is called 'induced drag'.
People will often say (eg about my car, that has measurable downforce), doesn't that downforce cause drag? The answer to that is 'yes' - but your car with lift also has drag!
That is, it doesn't matter whether the force is up or down; both cause drag.
Basically pretty well all cars on the road have lift. This can be measured very accurately with height position sensors on the suspension (my preferred approach)...
...or less accurately with electronic distance sensors looking down at the road. (I use ultrasonic sensors and an Arduino and a custom program I wrote in XOD visual programming language.)
So, unlike drag which is so hard to measure, lift/downforce is relatively easy to measure.
Many modifications that decrease wake area through long upper body curves (eg The Template) are likely, in my opinion, to generate a lot of lift. This can be measured, not only with the two above techniques, but also by directly measuring upper surface body pressures. This is easy and cheap to do with a surface pressure sensor (make it yourself), a Magnehelic gauge and a sealed reservoir.
I did testing of this sort on a Jaguar and then was able to compare my measurements with the official Jaguar CFD. They matched very well.
My measurements:
Jaguar CFD (hotter color = lower pressure):
Note the measured high lift on all the upper body curves eg windscreen header rail, roof, rear window. This pattern is measurable on all cars with these sort of upper body curves - and the longer they go for (eg The Template), the more lift (and so drag ) that is developed!
So it then becomes a balancing act, induced drag through lift versus less wake drag.
Unfortunately though, if you like driving, pretty well all lift is bad! However, an easy remedy is to use a very smooth undertray and so get high speed flow (and so low pressure) under the car. That counteracts lift, and of course reduces drag in its own right as well. (But only if you're not using a deep front airdam...)
As with upper body pressures, those under the car can also be directly measured, so you can see how well your undertray is working in developing low pressures.
Tl;dr:
- if your car has lift, it is getting drag from that source
- lots of techniques designed to reduce wake drag create lift
- but lift is easy to directly measure