My PT Cruiser will help us reach peak oil...

May 22, 2008 12:27 PM

Is there a way I can cost-effectively add more horsepower and/or fuel efficiency to my non-turbo PT Cruiser?

My mom just helped me buy a non-turbo automatic 2007 PT Cruiser through a car auction proxy (it's got 28,000 miles). It's my first car, and I got it for $9,000 when it sells for $15,000 new (Way more money than that $3 gas deal would save me), so I have to say I'm pretty happy. However, the fuel efficiency hasn't been so great. I get around 20 MPG doing my suburban driving with some highway driving peppered in. I typically go around 45-50 MPH. I used to drive my mom's Prius, so I'm a bit spoiled, milagewise. Also, I'm liking that there's more pickup to begin with on my car compared to the Prius, but I find that I sometimes have to floor it when I go uphill to get the car back to speed. I guess the Prius, with two engines and the battery, has more inertia. I should note that I tend to drive without heat/air conditioning, but I might open the windows a crack if they start fog up.

In the car reviews, I'm reading that the turbo version has great acceleration and slightly better fuel efficiency. Could I add a turbo at a price low enough that it'd be cost effective? (I'm thinking under $300?) And is it expensive to have a mechanic install it? Or is it easy enough for me to do it myself? I'm a pre-engineering education student (read:shop teacher) who just completed his freshman year, so I have some basic technical knowledge.

Or is there another tweak that could help me out? I'm debating taking out the rear seats when I drive alone (They slide out tool-lessly) and the spare tire (I have Triple A, so I'd assume they'd be equipped to deal with a flat).

Are my ideas any good? Am I overlooking any really simple option to get better milage?

posted by mccarty.tim to travel & transportation (31 comments total)

Removing your spare tire and relying on AAA is a waste of your time. Changing a tire is not the sort of thing that should require a phone call and a wait. You'll burn up as much fuel idling and re-starting your car as you do with the really insignificant weight of the tire. Removing the second row of seats will give you more cargo room, if only a tiny increase in fuel efficiency.
Power option: Just have the dead guy in back Flintstone it if need be.
posted by Inspector.Gadget at 12:35 PM on May 22

Adding a turbo for under $300 will be well-nigh impossible.

If I were you, I'd start out by getting an open-element air filter system, like this one from K&N. Though their horsepower gain claims are probably a little optimistic, you will see slightly better power and mileage by allowing your engine to breathe easier. It's also a fun and easy install and a good way to begin to familiarize yourself with your car.
posted by saladin at 12:36 PM on May 22

The turbo version may have better fuel efficiency but it will require premium gas in order to get that better efficiency.
posted by 517 at 12:42 PM on May 22

I should make it a bit more clear I'm not a car person, but I'm willing to learn some stuff to save some money and make the car work better. I will definitely look into the open air filter.
posted by mccarty.tim at 12:42 PM on May 22

@517: Good to know. That'll chew up any savings.
posted by mccarty.tim at 12:43 PM on May 22

You won't be able to add a turbo for $300.

Things you can do:

Replace your tires with lower rolling resistance ones when they wear out (this makes more difference than you'd think).
Keep your tire pressure relatively high (I inflate to 40psi).
Drive smoothly. Try to avoid braking as much as possible. You don't need more horsepower. If you never had to floor it, you'd be carrying around too much engine.
Keep the windows closed at highway speeds.
Keep your car well maintained with proper oil, etc.

But the best thing you can do is drive less.
posted by ssg at 12:49 PM on May 22

You won't find anything cost effective to add significant horsepower. Make sure the tires are all inflated evenly and properly.

This is not something you can do much about. You'll throw money at parts, and you'll end up spending way more than you'd end up saving in mileage gains. The irony here is that it is very easy to increase horsepower numbers (although not necessarily efficiency) on cars with turbochargers. But adding forced induction to a car is incredibly complex, even if there are retrofit kits for it out there. Some cars are better supported in the aftermarket than others. Even so, it requires changes to the electrical, exhaust, intake, and cooling systems. And that's just for a simple bolt on system. Often, a motor that was never meant to handle that much cylinder pressure and heat.. well it can't handle it. Cylinder walls warp, head gaskets expand, and many different engine fluids are suddenly friends when they aren't supposed to meet.

But, more on topic, try finding a simple cat-back exhaust, (basically the rear 2/3rds of the exhaust), an open filter, as was mentioned, and perhaps an ECU tune. I'm not even sure if anyone makes those parts. You might try Mopar.
posted by ninjew at 12:52 PM on May 22

Rather than repeat what everyone else said, I'll just point you to a PT Cruiser website.
posted by Floydd at 1:08 PM on May 22

I think ssg has it. The seats will make a marginal difference if you drive on hilly terrain. Overinflating your tires will also help, but is unsafe, yada yada. The only way to really save gas with a car that you already have is to drive it less, or drive it efficiently. Unfortunately driving it efficiently means driving like a granny. Plain and simple. Drive like you have an egg on the bottom of your foot. Gentle braking. Gentle acceleration. 60 mph MAX. It takes very little gas to keep going at a constant speed. It takes a LOT of gas to accelerate, and a lot of gas to push air out of the way above 55 or 60.

Myself, I go back and forth. I can manage granny driving (or "hypermiling" if you want to sound cool) for about a week, then I go back to regular driving.
posted by rhys at 1:09 PM on May 22

Just so you have some figures, with my 2000 Civic manual tranny, I get 30-32 if I flog it, and 38-40 babying it. So it does make a difference.
posted by rhys at 1:11 PM on May 22

It's easier to get better mileage with a stick, but here's what you can do:
Coast. On long downhills on the highway, stick it in neutral. Around town, drop it in neutral as soon as you see that the light ahead is red. If you see it turn red, shut the car down and start it back up when it goes green.

If you're in heavy-ish traffic, don't get anywhere near the guy in front of you. Like, you shouldn't be able to read his license plate. This will allow you to coast at the average speed of traffic instead of stop-starting. If people cut in front of you, Great! So What! Let 'em.

While accelerating, never let the revs (if you've got a tach) get above 2000 until you're in overdrive; i.e. don't leadfoot.

Change the fuel filter. If it's clogged, the whole system isn't as efficient.

Overinflate your tires, as mentioned above, but note that your braking distance will increase, esp on slick roads.

By shutting down the car whenever I coast or idle, and driving gentle (I still speed, I just speed a little later), I've gone from 28mpg to 36 (my last fillup was 43, but I don't believe it) in my '90 CRX with 218k miles.
posted by notsnot at 1:14 PM on May 22

I drove a (non-turbo, automatic) 2001 PT cruiser for 5 years. The gas mileage wasn't great, and it wasn't a speed demon, but it was a very reliable and generally practical vehicle.

Here is a bit of information that should add some perspective:
Your car is basically the stylized front half of a minivan strapped on top of a Dodge Neon powertrain.

This means that engine was originally designed for a smaller, more aerodynamic vehicle. Sure, it's been tuned and modified a bit - but not a whole hell of a lot.

Adding a K&N air filter and low rolling resistance tires are the easiest and biggest wins you can get for performance and economy.

Your other reasonable options include:
Replacing the stock exhaust system with a more free-flowing setup - but this can expensive and result in a much noisier car.

Chipping.
posted by terpia at 1:20 PM on May 22

In many states it's against the law to turn off the engine when the car is rolling. It's also dreadfully unsafe, especially if you have power steering or power brakes. Definitely not recommended.
posted by Class Goat at 1:21 PM on May 22

Not exactly the answer you're looking for, but we found that watching our fuel economy on a scangauge caused our gas mileage to go up significantly. (~15%). Of course, the thing that really made a difference was driving carefully like several people have suggested, but having that instant feedback seemed to help my wife and me. $160 from amazon.com.
posted by JMOZ at 1:25 PM on May 22 [1 favorite]

In many states it's against the law to turn off the engine when the car is rolling. It's also dreadfully unsafe, especially if you have power steering or power brakes. Definitely not recommended.

Seconded. And being as all modern cars have braking systems that require the engine to be running for maximum efficiency (ie vacuum assisted) this is indeed dangerous advice.

Your best bet is to drive with the minimum amount of momentum changes - try and drive at a speed that you can maintain and hold (safely) slowing down to speed up again uses fuel. Slowing down and speeding up within a shorter time/distance uses more fuel. Driving in a manner that reduces as much variation of speed as possible will give the best rewards.

Be cautious with the tyre inflation - you will lose a significant amount of grip and braking performance by raising the pressures. Moderation is key and economy cannot be your only consideration. Play close attention to tyre and car manufacturer guidelines and stay close to the upper limits that they prescribe.

As said before, there are no real cheap power +economy fixes (although there are for cars such as the High pressure direct injection models like the VW golf/jetta/bora/polo types). I'm not at all convinced about the K&N giving any significant advantage in power at lower revs (at higher revs, yes, but this is already negating any consumption advantage by revving the engine higher). It may well just be a placebo to change it and it needs regular cleaning to maintain the advantage it gives. The car's electronics, however, are not calibrated for the different flow resistance of this filter, so the gains are not at all guaranteed. As I say, you may get slightly better power, but this may be at the expense of economy anyway.
posted by Brockles at 1:32 PM on May 22

I wouldn't worry about dropping into neutral on hills and approaching stopsigns. The ECU is going to stop squirting fuel into the engine when you are "engine-braking", ie, your foot is off the gas and you're in a lower gear. Just take your foot all the way off the gas.

As far as shutting the car off, if I'm in the mood, I will do it when stopped at a light that I know is fairly long. It does make a difference if you've got a lot of lights in your drive. I don't feel comfortable shutting the engine off while the car is moving, and I believe it is illegal.
posted by rhys at 1:33 PM on May 22

Will the break lights remain on if I shut off the engine? Also, about how much should I expect to pay for new high rolling resistance tires? I'm worried about over-inflating right now, because the car skids too much as it is, since I don't have ABS and am not the best at pumping yet. However, I will keep it at manufacturer's spec.
posted by mccarty.tim at 1:50 PM on May 22

Also, about how much should I expect to pay for new high rolling resistance tires?

I bought these Sumitomo tires for a little more than $200 for a set. Rolling resistance varies quite a bit between different tires and often isn't easy to find out the rolling resistance of a particular tire, so you need to do some research. You want low rolling resistance tires, of course.
posted by ssg at 2:02 PM on May 22

Will the break lights remain on if I shut off the engine?

Yes.
posted by mr_roboto at 2:05 PM on May 22

I once heard the phrase, "It's not how fast you want to go, it's how fast you want to spend."

Holds true here. More speed = more expense, whether you're considering buying performance parts or just flooring it.
posted by crunch buttsteak at 2:45 PM on May 22

the spare tire (I have Triple A, so I'd assume they'd be equipped to deal with a flat).

They will come and help you put on your spare, but do not carry with them spare tires to fit any car they might meet, nor would one usually repair a flat tire by the side of the road (even if the tow truck carried with it all the tools to do so, which is unlikely). So this is a bad idea.

There are no easy, cost-free solutions to this -- otherwise, everyone would be doing it already, and the US auto makers who are being killed by high gas prices would quick spiffy up their vehicles to get 150mpg. You can do small things (like watch tire pressures, etc), but pretty much everything has a compromise. An aftermarket air filter might invalidate part of your warranty; those over-inflated tires will make it easier to skid in the rain; etc. Driving slower and smoother will save you lots of gas, but will sometimes get you honked at by other drivers. Being religious about maintenance (oil, filters, tire pressures, etc) will help a lot, too.

Basically, if you really care about fuel economy, you would buy a different car. You got a good price on this one, but it means you will have to live with unexceptional fuel economy.
posted by Forktine at 2:51 PM on May 22

There's not a lot that I can think of that you can do cheaply. Additionally, increasing horsepower and fuel efficiency is gonna be sort of difficult. In general, most things that you can do to increase horsepower will not positively affect your fuel efficiency.
posted by anansi at 3:01 PM on May 22

Unfortunately for your pocketbook, these answers are pretty much correct. The PT Cruiser is a lot of car for the base engine that they put in it. I'm sure the '07 is similar to the '08, and I was surprised at how narrow the spread is between highway and city mileage.

Aftermarket air filters cannot invalidate the warranty, there is some law about that. Something like a K&N filter might be helpful- what it does is reduce the amount of energy the engine wastes trying to suck air through the filter. Its effectiveness at making a noticeable improvement depends on how "bad" the existing filter is, and how much the engine is really working to overcome it. When you are driving, most of the time the throttle is not open very much at all, and the existing filter can easily provide the air the engine requires. But over the life of the car, a well maintained K&N will at least pay for itself in not having to buy new paper filters all the time. You just have to clean the thing every 3-6 months.

I've had good luck with keeping the tires well inflated. Nothing drastic, but I haven't seen any downside- they are actually wearing more normally now. I think the factory pressure for my car was too low. I can see the difference in MPG if I forget to fill them up for a while.

As for going into neutral during deceleration, I've heard that it's actually not helpful, and might actually use more fuel. It was explained like this: an idling engine has to expend energy to keep itself turning and powering the air conditioner, alternator, etc. But if it's still in gear when you are slowing down, the inertia of the car is actually turning the tires and thus the engine, and thus the accessories. It's using no, or almost no, fuel.

But the end game is the same- the engine will burn enough gas to meet the power demand you ask of it. And gasoline engines are not linear in their power/RPM/fuel usage curves. You'll get the optimum use of your fuel dollar if you learn the "sweet spots" of your car. See this site for a ton of graphs and a good explanation.
posted by gjc at 3:18 PM on May 22

K&N air filters need to be cleaned and re-oiled about every 50,000 miles, not every 3-6 months. Actually, it is easy enough to put too much oil on, leading to a fouled MAF sensor that needs to be replaced, that it is probably a better idea to just replace the K&N filter at that point.
posted by kindall at 3:31 PM on May 22

Thanks for all the suggestions, guys. I think the main thing is that I'm just kind of in shock driving a "regular" car after riding in a hybrid for a year.
posted by mccarty.tim at 3:51 PM on May 22

but I find that I sometimes have to floor it when I go uphill to get the car back to speed

Revise your driving habits. You should never need to do this, not only is it bad for the engine but consumes more petrol very inefficiently.

Also... "getting up to speed" is a myth. There is no speed to get up to apart from the legal limit, and there is no legally imposed time limit for you to reach the limit.

The PT Cruiser suffers from a large, overly styled body on a 2 litre engine, it's never going to be a great efficiency performer.
posted by mattoxic at 5:21 PM on May 22

I'm worried about over-inflating right now, because the car skids too much as it is, since I don't have ABS and am not the best at pumping yet.

Under what conditions does the car currently skid? Going around curves? When coming to a stop? Other?

Unless you're driving on snow or ice or there's something seriously wrong with your car, I suspect that your driving style may be hindering your fuel efficiency if you're skidding your car more than, say, a couple times a year.

If you find yourself often needing to stop so suddenly that you're skidding or having to pump the brakes, you could probably improve your gas mileage (and safety) by looking and planning ahead far enough to avoid using the accelerator in situations where you will almost immediately need to turn around and use the brakes.
posted by Juffo-Wup at 9:11 PM on May 22

@Juffo: It's only happened on the really rainy recent days during turns. Turns which my mom's Prius (complete with VSC and ABS) could handle pretty well lead to a bit of skid on the PT Cruiser. My town has a lot of sharp turns next to stretches of road that go at highway speeds. Worse, my vision of those turns is often obstructed by trees and turns in the road. I've been having to drive to the community college I've never had to go to before for a summer course, and that calls for turns I'm not familiar with. I ordered a GPS unit on Ebay, so that should help me better predict my turns...
posted by mccarty.tim at 9:56 PM on May 22

If the skids are on wet turns, then your problem is not in your brakes. Your problem is that your new car weighs about 500lbs more than your old car. You need to drive more slowly, and you especially need to drive more slowly in the rain. If curves can jump out at you so fast that you simply don't have time to slow down enough for them, then you just need to be driving more conservatively. Your GIS should be for directions, not to warn you of road conditions. If you came around one of those blind turns and there was a car stalled in your lane, would you have time to avoid it?
posted by agentofselection at 10:38 PM on May 22

And the weight distribution of the car is biased towards the front a lot more than in a Prius.

In fact, I was just treated to that physics lesson yesterday! I was driving down a road doing 20-25. Another driver blows her stop sign (but wasn't going very fast at all- 5-10 mph (she "thought she could make it past")) and hit the very back of my car (similarly front heavy). Spun me 180 degrees on dry pavement.

If you can't see far enough ahead to predict your turns, you are going too fast.
posted by gjc at 7:08 PM on May 23

Turns which my mom's Prius (complete with VSC and ABS) could handle pretty well lead to a bit of skid on the PT Cruiser. My town has a lot of sharp turns next to stretches of road that go at highway speeds. Worse, my vision of those turns is often obstructed by trees and turns in the road. I've been having to drive to the community college I've never had to go to before for a summer course, and that calls for turns I'm not familiar with.

Everything about your 'explaining' why your car skidded says to me that your driving - and more importantly your planning and awareness - are very much in need of serious scrutiny. Black ice or sudden appearance of wildlilfe/trees falling over are really the only sort of things that make your car skid unexpectedly. Anything else is lack of awareness and inappropriate speed - ie bad driving.

If you can't see, slow down. If you don't know what is around a corner, slow down until you are at a speed that anything around there is easily dealt with/avoided. Driving in a manner that relied on the fancy electronics in the Prius to deal with is lazy driving and poor planning. I suggest a very serious look at your appreciation of potential dangers before it is too late and you find out the hard/painful/expensive way that you have been living a lot nearer the edge than you have been prepared to admit to yourself.
posted by Brockles at 10:49 AM on May 25