News Culture

Why Car Companies Want to Dyno Test Cars They’ve Already Sold You

The EPA's In-Use Verification Program (IUVP) is part of how the government keeps track of automotive emissions on cars with real-world miles on them.
Toyota Prius dyno testing.
Toyota (YouTube screencap)

Would you let Toyota borrow your car for a couple of weeks to run tests on it? From the onset, that might sound a little ominous. But it’s actually common practice for an automaker to test the emissions of its cars that have real-world miles on them. If you get a letter from the company that made your vehicle offering compensation to let them run it on a dyno, it might not be a bad deal.

This week a thread on Twitter came up on my radar in which somebody with a Tundra shared a letter from Toyota asking to borrow their truck in exchange for a loaner vehicle for “up to two weeks” and $300. User @BradWrench accompanied that with a comment along the lines of “hell no I’m not letting you torture my truck for a measly $300.” I probably would have had the same initial reaction. But as Jalopnik’s Editor-in-Chief Bob Sorokanich pointed out, this kind of dyno testing is not about measuring max engine power or automotive torture testing.

The exchange made me curious, though — why did Toyota want this dude’s Tundra at all? A little research led to my discovery of something called “CAP 2000” and how automakers regularly borrow civilian-owned cars for spot-check emissions testing. Here’s what you should know about it.

An In-Use Verification Program (IUVP) is what’s being referenced in the letter in that tweet. And the impetus for such a thing is regular EPA compliance for the automaker. Practically speaking, Toyota asking to borrow that Tundra is not necessarily indicative of a brewing emissions scandal nor is it necessarily a bad idea to let the company have the car for a while in such a situation. It’s just something the automaker’s mandated to do in order to continue doing business.

I did reach out to Toyota’s U.S. government and compliance media contact who said as much — IUVP testing is mandated for all automakers by the EPA and has been for some time. Indeed, the EPA’s policy called CAP 2000 (a Compliance Assurance Program written to start with model year 2000) specifies that. You can follow that link to review the whole document if you’re so inclined but I’ll save you the click and share the paper’s Background section wholesale right here:

“EPA’s vehicle certification program requires manufacturers to demonstrate that new cars and light-duty trucks meet the required emissions standards prior to offering new models in the commercial marketplace. EPA then issues a certificate of conformity permitting the sale of those vehicles. Given the generally stable state of emissions control technology on today’s cars and trucks, coupled with in-use compliance programs, it was believed that certification requirements could be streamlined, with greater emphasis placed on in-use performance.”


The EPA itself states that it runs its own tests like this with privately owned cars from volunteers, evaluating about “150 customer-owned vehicles per year through this surveillance program.” Automakers and their contractors do more. Specifically, OEMs have to “demonstrate in-use emission performance by testing more than [2,000] in-use vehicles per year” per CAP 2000.

Toyota does happen to have a nice little informational website on the matter, which you can find at It’s explained that the testing is pretty much just a scientific sniffing of your car while it’s parked, refueling, and rolling along at various but modest speeds for about 90 minutes in total. In Toyota’s case, the automaker is looking to measure outgassing and tailpipe emissions on cars from two groups: Ones that have been on the road for about a year and 10,000 miles, and ones that have been driving for about four years and 50,000 miles.

Here’s what an In-Use Verification Program (IUVP) test on a Toyota entails:

If you are thinking about loaning your car to the EPA or an automaker for an IUVP test (they are voluntary from the consumer’s standpoint, after all) here’s what you can expect will happen to it based on Toyota’s briefing:

  1. The car will be in the automaker’s possession for up to two weeks and could come back to you with as many as 150 more miles on it.
  2. The car will be inspected by technicians and potentially serviced. After all, automakers are incentivized to get maximally efficient performance out of the vehicle here since theoretically, they’ll be reporting their true findings to the EPA. So with that in mind, if you have a custom engine tune or exhaust modifications to your car I wouldn’t bother letting the automaker borrow for this because they’ll probably send it right back with a “no thanks.” But if you’ve got a stock vehicle, I wouldn’t be surprised if the company slaps a new air filter or PCV into your Corolla or whatever without charging you. Confirm this with your contact before agreeing to anything, though.
  3. The car goes through three tests on a dyno, which for those who don’t know, is basically a treadmill for cars. As Toyota details:
    • “City driving is simulated by a cycle called the Federal Test Procedure (FTP). The cycle has an average speed of 21.2 mph, lasts approximately 30 minutes, and is conducted in three phases.”
    • “Highway driving is simulated by the Highway Fuel Economy Test (HFET or HWY). This test has an average speed of 48.3 mph and lasts just under 26 minutes.”
    • For supplemental testing — “The US06 cycle was created to test vehicles under high speeds and acceleration conditions that more closely resemble modern driving habits. The test lasts 20 minutes with an average speed of 48.4 mph and a brief high speed of 80.2 mph.”
  4. The car also undergoes evaporative testing. That means vapors from a parked car (plastics and various other automotive materials emit them, even at rest) are measured with both the car sitting by itself and while it’s refueling.
    • Specifics on the parked car outgassing test: “Vapors from a parked vehicle’s fuel tank are collected in a canister, but can potentially escape in small amounts. In addition, the rubber in tires and wiper blades, the plastics in panels and trim, and other materials on the vehicle can give off small amounts of vapors. To confirm the impact [of] these components, a vehicle is placed in a sealed room called a Sealed Housing Evaporative Determination, or SHED, chamber. Inside the SHED chamber, the temperature is cycled between 77℉ and 95℉ over a period of two to three days while the air in the room is monitored for vapors.”
    • As for fueling, the canister that collects vapors in your car’s fuel system is tested with an “On-board Refueling Vapor Recovery, or ORVR, chamber. The vehicle is connected to a fuel pump nozzle like those at a gas station, and sealed in the ORVR chamber. The air in the room is then monitored for vapors while the fuel tank is filled.”
  5. Being parked and maybe shuffled around a garage or lot should be pretty much the only other activity your car gets up to while it’s in the automaker’s possession for an IUVP test.

If you get a letter from your automaker asking to borrow your car for such a test, you don’t need to worry that your car’s going to be redlined for two weeks under Davis Dam towing conditions. In fact, it might be a nice opportunity to drive something else for a few days while the car company sniffs your car. Heck, you’re also getting a factory inspection out of it and maybe a tech will spot an issue you hadn’t noticed.

Just make sure to confirm that whatever letter you get is legit, and take the time to find out if your car will be subjected to anything outside of what’s detailed above for your own peace of mind. Then take all your important personal items and anything identifying out of the car before you hand over your keys. But that should be standard practice any time you leave your machine with somebody for service for an extended period of time.

Have you ever had an automaker borrow your car for this kind of testing? I’d be very interested to hear about your experience in the comments section below.