This time, it's Hypertech and the new Max Energy programmer. The expectations have been ratcheted up this time, with big and bold claims of huge gas mileage savings, 50+ horsepower for gas vehicles and 120+ for diesels, plus the alleged ability to get big gains on low-octane gas. Enthusiasts who know less about cars and performance have been sent off drooling; gearheads remain quite skeptical.

Let's look at the horsepower gains first, starting with the claimed 50+ boost to gas vehicles. Of course, you can't get this with every vehicle the Max Energy fits. This dyno-proven gain belongs to the Ford Shelby GT. Vehicles with less displacement and considerably less performance equipment can't expect to get even half that much of a gain. Most of the gas trucks will be in the 20 range. Only the Hemi-powered DC cars can get up to that mid-20s range too; smaller V6s won't even get close. Because of the massive compression, diesels can see some unruly gains from this type of programming. The Max Energy also claims to keep these diesels from suffering high EGT damage, thanks to tuning that keeps power high without over-fueling, even when towing. And, it claims to not de-fuel and kill your momentum.

The big problem with the big power gain claim is this: huge, noticeable HP boosts only happen at RPMs most drivers won't reach?especially if they have an automatic. Peak horsepower usually happens around 4500-5500 RPM. That's not to say the smaller gains at lower RPMs won't be noticeable, but the impressive power only happens when you're really gunning it.

On to the gas savings claims. This feature is one of the main reasons programmers have become so popular in the two years since $3/gallon became the societal norm. Programmers didn't previously sell themselves on mileage, but began doing so once the big pinch at the pump began. Hypertech reports test vehicles gaining up to 6 MPG, with others settling in the 1-2 MPG gain range. In terms of real-world experience with programmers and mileage, the gains are almost always more modest than the ad claims. A boost of 1-2 MPGs'if any gain is achieved'is the most common scenario. Many drivers see no mileage gains because they simply can't keep their foot far enough out of the gas pedal.

Some features of the Max Energy are undisputable. The ability on most vehicles to change tire size for odometer and speedometer corrections is great. Reading engine trouble codes is a mainstay of programmers; it's present here too. Fuel octane settings are also available for some models to help save some coin at the pump. But, it's not available for performance cars, and as you adjust the octane down, the power also goes down.

The bottom line on the Max Energy: set realistic expectations before you buy. The massive horsepower gains in the ads are probably far from what you'll actually get, but you will get enough of a gain in power to notice it everywhere you drive. For gas mileage, don't expect this programmer to save you from all of your petrol peril. Gaining 1-2 MPG is realistic if you're not racing; anything more is gravy. If you can also make use of the other cool features, this new programmer is a solid buy. If you were hoping to get 50 hp more, save 6 MPG and run all on ethanol, you may want to pass until a programmer that can do all of those things exists.