GT7 Aerodynamics

I’ve been playing Gran Turismo since the first version on the PSone, and I still grab my controller a couple times a week and get in 26.2 miles to earn my “daily disappointment” (a roulette prize wheel that always seems to land on the most worthless prize).

GT7 touts itself as a racing simulator, but its aero modeling sucks. I understand why they did this, to protect the game’s leveling system, called Performance Points (PP). In the real world, downforce benefits you in fast corners, the faster the corner, the more benefit. In order to balance that in the game using their PP system, every car would have a different PP value at every track. That’s too complicated, so Gran Turismo simply made aero less effective.

How much less effective? I’m glad you asked! To find out, I built four cars with exactly the same weight, power output, suspension, ground clearance, etc., but very different aero.

I had to buy ECUs, power limiters, and ballast to make them all equal weight and weight distribution, and then I put them all on Sport Medium tires.

I chose the Subaru BRZ and Toyota GR86 because there are a few different versions of the car, but one could do this experiment with a Mustang, C7 Corvette, or other car that has both street and racing versions.

I used Watkins Glen for the race track, because it has fast corners where aero is effective. At least in the real world. In the Gran Turismo world, aero is virtually meaningless:

Build	Front / Rear DF	Grip @ 75 mph	Lap
No aero 524pp	0 / 0	1.18g	2:06.845
Street aero 545pp	200/300	1.22g	2:07.006
Group 4 532pp	200/350	1.21g	2:07.076
Group 3 549pp	500/800	1.29g	2:06.730

As you can see, the car with the most downforce (1300 lbs), set the fastest lap, but only by a tenth of a second! In second place was the car with no aero at all, and it came in at 524 points versus 549 points for the Group 3 car. In the real world, you’d see a few seconds between a car with no aero and a car with a simple splitter and wing.

So are the aerodynamics in GT7 totally worthless? No. I discovered that the downforce values are fairly accurate, and the car data can be used for research.

Downforce values in GT7

In GT7 all cars with aero are given front and rear downforce listed in pounds. For example, a Toyota GT-One has 600 lbs of front downforce and 900 lbs of rear downforce. But what speeds are those values based on? After some investigation, it appears to be at about 130 mph (210 kph).

I’ve come to this conclusion by comparing the real-world downforce values for several to the downforce values in the game. To get the real-world values, I went to Muslanne’s corner and noted the downforce values for every car (at 150 mph) and threw them in a spreadsheet. I then compared that to the same car in Gran Turismo, factored in the speed, and came out with 130 mph as being very close.

Another car that helped me figure out this value was the Porsche 911 GT3 RS, which reportedly makes 895 lbs of downforce at 124 mph. By factoring in a speed change to 130 mph, I got 984 lbs of downforce, which is close enough to GT7’s figure of 1000 lbs.

So here’s a smattering of cars in GT7 and their approximate coefficient of lift (cL), which is inverted here to mean downforce. If you’re not familiar with coefficients, check out my article on Thinking in Aerodynamic Coefficients to see examples of various cars and how much downforce and drag they make.

Car	Front	Rear	Total DF	cL	% F	Drive
Formula	1500	2000	3500	4.20	42.9%	MR
GT-R LM	1400	1400	2800	3.43	50.0%	FF
RB X2019	1000	1600	2600	3.20	38.5%	MR
Valkyrie	1000	1500	2500	3.05	40.0%	MR
Gr 2, GT500	750	1150	1900	2.33	39.5%	FR
GT-One	600	900	1500	1.84	40.0%	MR
BRZ GT300	500	800	1300	1.37	38.5%	FR
Group 3	450	700	1150	1.21	39.1%	FR
911 GT3 RS	350	650	1000	1.06	35.0%	RR
Amuse S2K	350	550	900	0.95	38.9%	FR
Group 4	200	350	550	0.60	36.4%	FR
RX7 GTO (real)			525	0.57		FR
Street car aero	200	300	500	0.59	40.0%	All
RE-RX7	150	350	500	0.59	30.0%	FR
RCR Civic	200	250	450	0.53	44.4%	FF
Miata touring	70	350	420	0.50	16.7%	FR
LP 750-4 SV ‘15	150	250	400	0.42	37.5%	MR
C7 ZR-1	150	250	400	0.42	37.5%	FR
Gr 3 road car	100	200	300	0.32	33.3%	All
930 Turbo	100	150	250	0.27	40.0%	RR
Cayman GT4	80	160	240	0.26	33.3%	MR
911 GT3 (996) ‘01	30	120	150	0.16	20.0%	RR
C8	50	80	130	0.14	38.5%	MR
M2C	20	40	60	0.07	33.3%	FR
911 RS SC (993) ‘95	0	60	60	0.07	0.0%	RR
NSX Type R	25	25	50	0.05	50.0%	MR
WRX ‘99	0	40	40	0.04	0.0%	FR
GR Corolla	0	20	20	0.02	0.0%	FR
E30 M3, 190 Evo	0	0	0	0.00	0.0%	FR

I’ve also added the front aero load distribution (% F) and the drivetrain layout to the table. Many people say you should match aero distribution to weight distribution, but I don’t subscribe to that theory, and neither does Gran Turismo (or the real-world values in Muslanne’s database). You can see that aero distribution is typically around 40% front (meaning more rear aero), regardless of drivetrain layout. Even the front wheel drive Nismo GT-R LM car has a 50/50 aero distribution, despite having 65% of the weight on the front tires.

You’ll also notice that some cars that probably do have some downforce, such as the E30 M3 and 190E DTM cars are listed as having no downforce in GT7. And the Miata Touring car can somehow make 350 lbs of downforce, despite being a convertible. (In my real world testing, a convertible top made 40% of the downforce as a hardtop.) There’s also no concept of lift in the game, and as you might know, most street cars make lift, and cars with zero lift are rare. Anyway, it’s a game afterall, and I’m sure there are many other oversights and some mistakes (and that goes for this article as well).