You Should Not Tune Your Daily Driver



The Fast and Furious franchise gets a lot wrong when it comes to tuning cars – but what thing it gets mostly right is the spirit of family that comes with that lifestyle.

Normal people don’t tune their cars,” the great Jack Baruth told me, years ago. “Normal people buy Camrys and don’t think about their cars at all until it’s time to buy their next one.”

He’s right, of course, but it’s nice to feel normal, and I’ve surrounded myself with a family of go-fast car and motorcycle people ever since. Recently, one member of that little family decided to sell his daily driver – an utterly unmolested and squeaky-clean W211 Mercedes-Benz E55 AMG – and that’s where my trouble started.

Like any good friend – sorry, family member –  I wanted to help. I got some of his pictures and wrote the following post on the local Facebook dads’ group:

OK, dads, this is a special one for anyone interested in these cars. [Tuner guy’s name deleted] believes you don’t tune your daily, and has owned this car for several years. It’s clean, bone stock, and the last of the big blown AMGs. Reach out if it’s your bag, baby.”

The first comment, right out of the box, had nothing to do with the car, nothing to do with the price, and nothing to do with the car’s well-known owner. It was this:

You don’t tune your daily? Had to check to see if this was posted in the mom’s group.”

It was a comment which – my knee-jerk accusations of sexism, toxic masculinity, and baby-dicks aside –actually did lead to some interesting questions being asked. Namely, why shouldn’t you tune your daily? And, considering I’ve spent the better part of my career trying specifically to convince people to tune their cars, I felt like it might be interesting for me to try to answer that question here in a frank, open, and honest way. You know, like, I could tell the truth. About cars.


Now, when people talk about tuning their daily drivers and building them for performance, the general assumption is that we’re not talking about six-figure German muscle cars or twin-turbocharged Japanese techno-rockets here. I’d argue that those guys have the money to break a transmission here or there and deal with it, if begrudgingly so, so let ‘em. Instead, I’m talking about the guys and gals who start to earn a living wage for the first time in their lives and decide to spend some of their newly-earned dollars on high-performance go-fast parts for their – I dunno, let’s say it’s a 2009 Mk6 VW GTI.

At 12 years old and with something around 120,000 miles on the odometer, that ’09 Mk6 GTI might have plenty of life left to it. That’s especially true if it’s been properly and meticulously maintained – but it probably hasn’t been, and that brings me to this simple explanation for ECU tuning – commonly called “chip tuning” – that I was given as a fresh-faced, doe-eyed innocent on one of my first days at RENNtech way back in the early aughts.

“The manufacturer builds in x amount of performance in their engine, and n reliability,” the explanation went. “And whenever you tune a car for more performance, you’re subtracting from n to get more x.”

I’m sure you can see where I’m going with this, but that’s probably because you’re a mature human who understands that “Stage 1” and “Stage 3” are just marketing terms meant to capitalize on the popularity of Gran Turismo, and don’t have anything to do with objective reality. In case it’s not obvious, I’ll spell it out: that 12-year-old car doesn’t have enough n left for you to get the amount x you want out of it, and you should leave it alone.

And that’s just engine tuning – we haven’t talked yet about suspension tuning with lowering kits or stiffer springs that put different loads on different parts for different amounts of time than they were designed to handle. What about brakes, wheels, and tires? If you’re making your car go faster in a straight line, how are you planning on managing that extra speed once it’s time to stop or steer? Can you afford to do what’s right, here, or are you deciding what the engineering priorities should be based on some dubious metric like, “APR is having a 20 percent group buy on …”?

Of course, I’m making a lot of assumptions here. I’m assuming that you’re driving a 12-year-old GTI because you can’t afford a new one. I’m assuming that you probably don’t have the ready cash to replace a failed turbocharger or scattered DSG, too. Finally, I’m assuming that you have not gone from stem to stern on the thing replacing all the ball joints, bushings, bearings, or any parts that start with any other letters of the alphabet, either. I’m assuming that the car gets you from A to B well enough, and you’re gambling that it can handle whatever extra strain you’re about to throw at it.

Which begs the question: if you haven’t gone through the car from bumper to bumper, how do you know it can take it?

You don’t, and you used to see the results of these failures all the time on forums like 6SpeedOnline years ago, with for sale posts about cars that were just about to pop.

“I’ve had a lot of fun with this car, as you all know from my other posts and videos,” they read. “But it’s time for me to move on to my next project, and I want this car to go to a good home …”

That’s another rude awakening coming to first-time budget tuners. All that money you spent on your car? Not only will you not get it back when it comes time to trade in that car at a dealer, but you’ll also probably get less for your car than someone who left their Mk6 GTI stock … it’s an especially painful realization because, to you, you’ve genuinely tried to make the car better. It’s the same hurt I’ve seen on the faces of guys trading in their customized Harley-Davidsons. Some of these guys spend $20,000 on a bike, another $20,000 on chrome and handlebars and paint, and just die inside when you explain that, all that money they spent getting their ride “just right” really took its market appeal from “as broad as possible” to “you are the only person who could possibly love this metal flake yellow and brown monstrosity – and why is there a werewolf playing the guitar on it?” You know?

You do know – but before I let you go; I will acknowledge that there may be some exceptions to the whole “you’re going to break it” thing. And, since no internet argument is complete without a villain, I’m going to give you one: The marketers.

At least, I assume it was the marketers who decided that a 2011 Mercedes-Benz SLK350 could reliably and dependably and responsibly handle 300 hp when that same, fundamentally identical powertrain in a less expensive C350 of the same vintage could only handle 268 hp. It shouldn’t be much of a surprise, then, to learn that my favorite “tune” to put on the C and E350s back then was just the stock SLK350 file. It made the cars noticeably more responsive and heck, the dealer could even scan the thing and it wouldn’t trip any alarm bells. Why would it? It was a valid MB file!

There are a few other weird deals like that. The 3rd gen Toyota Supra had an easily defeat-able fuel cut that limited its output as part of a bizarre “gentlemen’s agreement” that Japanese automakers once had to not sell cars with more than 280 hp. Removing that effectively changed nothing, but “released” about 40 wheel hp, so that was nice.

Still, these are exceptions that prove the rule – and, yes, you might find a few VWs or Buicks that have been neutered by the marketers to protect the price gap to their more expensive Audi or Cadillac siblings, but if you can’t afford a new one, well – you probably shouldn’t be messing around with an old one. In fact, that’s good advice: before you start tuning your daily, buy a backup daily to get you back and forth to work. That could even be something interesting and fun instead of boring and lame, as Corey Lewis has done a great job of pointing out.

So, be smart. Don’t tune your daily. And, if you already did, I’m sure your car is different and you’ve made a fine life choice there. Have a great day!

[Image: Joyseulay/]

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