Compression Test Kit By Harbor Freight Item #39224 on 2040-parts.com

London's GPS-based speed-limit trial puts Big Brother's foot on the gas pedal

A fleet of 12 Toyota Priuses in London have been fitted with GPS-linked speed limiters to measure how drivers respond to having their speed controlled by a computer rather than their own feet. For now, the trial is local to London, run by Transport for London, the agency that manages the city's roads, buses, subways and trains. The agency is using its own fleet of Priuses for the test and will add a bus and a taxi later this year.

BMW debuts social-media campaign for concepts

BMW launched its next marketing campaign for the BMW i3 and i8, aimed at the tech consumer. The campaign runs on location-service Foursquare, social-news round-up site Mashable and iAd, Apple's mobile-advertising network. The iAd campaign will run in Europe on iPhones, iPods and iPads.

Porsche Cayenne S Diesel: The V8 diesel Cayenne arrives

Porsche has revealed the 2013 Cayenne S Diesel with a 4.2 litre V8 diesel offering 378bhp, 626lb/ft of torque and 0-62mph in 5.7 seconds. Back in April we reported that the Porsche Cayenne S Diesel was on its way with a V8 diesel engine to take on the BMW M50d and the upcoming offerings from Land Rover with a 2014 4.4 litre Range Rover Sport seeming a likely possibility. Now Porsche has caught up and revealed the Cayenne S diesel, which gets the 4.2 litre diesel V8 with a healthy 378bhp and a very useful 626lb/ft of torque, enough to scoot the Cayenne S Diesel to 62mph in 5.7 seconds – a bit slower than the M50d, but all that torque should make it feel at least as lively.